Morphology, variation, and systematics of the late Cambrian Laurentian dikelocephalid trilobite Walcottaspis vanhornei (Walcott, 1914)

Abstract: Walcottaspis vanhornei (Walcott, 1914) is a large, late Cambrian trilobite with a unique pygidial morphology known only from a narrow outcrop belt of the St. Lawrence Formation in the Upper Mississippi Valley. Found in carbonate-rich layers within heterolithic facies that represent the toesets of a prograding shoreface, it is restricted to a single or small number of parasequences. Only four specimens of any of its sclerites have been illustrated previously. Here holaspid examples of all its biomineralized sclerites are described and illustrated, along with a morphometric analysis of cranidial landmarks and landmarks plus semilandmarks for the pygidium. Ontogenetic allometry accounts for 29% of the variance among holaspid cranidia and includes a relative shortening and narrowing of the palpebral lobe and a reduction in the relative length and width of the frontal area. Notable pygidial phenotypic variation occurs in the extent of the postaxial region and in the proportion of the structure occupied by the axis. Phylogenetic analysis suggests that W. vanhornei is sister taxon to Dikelocephalus minnesotensis Owen, 1852, which also occurs in the St. Lawrence Formation and has a broadly similar cephalon but distinctive trunk. The holaspid pygidium of W. vanhornei is uniquely characterized by the interpleural furrows of the first two segments becoming abruptly obsolete on approaching the axial furrow. Some pygidia show narrow, shallow, flat-bottomed grooves etched into the internal sides of the dorsal surface or doublure that apparently represent infestation of the live trilobite.

trilobite
walcottaspis vanhornei
narrow outcrop belt
morphology


Microtoid cricetids and the early history of arvicolids (Mammalia, Rodentia)

Abstract: In response to environmental changes in the Northern hemisphere, several lines of brachyodont-bunodont cricetid rodents evolved during the Late Miocene as "microtoid cricetids." Major evolutionary trends include increase in the height of cheek tooth crowns and development of prismatic molars. Derived from a possible Megacricetodon or Democricetodon ancestry, highly specialised microtoid cricetids first appeared with Microtocricetus in the Early Vallesian (MN 9) of Eurasia. Because of the morphological diversity and degree of parallelism, phylogenetic relationships are difficult to detect. The Trilophomyinae, a more aberrant cricetid side branch, apparently became extinct without descendants. Two branches of microtoid cricetids can be recognized that evolved into "true" arvicolids: (1) Pannonicola (= Ischymomys) from the Late Vallesian (MN 10) to Middle Turolian (MN 12) of Eurasia most probably gave rise to the ondatrine lineage (Dolomys and Propliomys) and possibly to Dicrostonyx, whereas (2) Microtodon known from the Late Turolian (MN 13) and Early Ruscinian (MN 14) of Eurasia and possibly parts of North America evolved through Promimomys and Mimomys eventually to Microtus, Arvicola and other genera. The Ruscinian genus Tobienia is presumably the root of Lemmini. Under this hypothesis, in contrast to earlier views, two evolutionary sources of arvicolids would be taken into consideration. The ancestors of Pannonicola and Microtodon remain unknown, but the forerunner of Microtodon must have had a brachyodont-lophodont tooth crown pattern similar to that of Rotundomys bressanus from the Late Vallesian (MN 10) of Western Europe. Possibly, Pannonicola and Microtodon share a common ancestor. The fossil record suggests that an important center of origin for arvicolids was located in northeast Asia. From this region arvicolids could have dispersed to Europe and North America and vice versa during the late Cenozoic at various times.

arvicolid
north america
asia
microtoid cricetid


Proterochampsa barrionuevoi (Archosauriformes: Proterochampsia) from the Late Triassic (Carnian) of Argentina and a phylogenetic analysis of Proterochampsia

Abstract: Abstract:  Restudy of skulls and available postcrania of the proterochampsian archosauriform Proterochampsa barrionuevoi from the Ischigualasto Formation (Upper Triassic, Carnian) in the San Juan Province, Argentina, confirms that the genus is diagnosed by autapomorphies that include dermal sculpturing consisting of prominent ridges and nodular protuberances, a large hook‐like lateral projection on the quadratojugal, an antorbital fossa restricted to a depression along the maxilla, lateral expansion of the premaxilla anterior to the premaxilla–maxilla contact, absence of a supratemporal fossa, exclusion of jugal from suborbital fenestra, basal tubera of parabasisphenoid facing ventrally and reaching laterally beyond the basipterygoid process, and a ventral lamina on the angular. Proterochampsa nodosa is a valid species distinguished from P. barrionuevoi by fewer cranial ridges with larger protuberances, relatively smaller supratemporal fenestrae and width of frontals between orbits less than that of the nasals. A phylogenetic analysis supports the monophyly of Proterochampsia consisting of Proterochampsa, Chanaresuchus bonapartei, Gualosuchus reigi, Tropidosuchus romeri and Cerritosaurus binsfeldi. A temporal separation between the two basal proterochampsians with earliest records in the Late Triassic (Proterochampsa and Cerritosaurus) and Chanaresuchus, Gualosuchus and Tropidosuchus in the Middle Triassic indicates hidden proterochampsian diversity in the Middle Triassic.

proterochampsia
late triassic
phylogenetic analysis


Stability, ranks, and the PhyloCode

Abstract: Current codes of biological nomenclature define taxon names using types and ranks: the type determines the minimal membership of a named taxon, and the rank is supposed to determine its limits. Homo is "the taxon including the type species Homo sapiens that is assigned to the rank of genus". However, there is no "genus concept" (analogous to a species concept), and thus no way of empirically determining the limits of a particular genus, even in the context of a single agreed phylogeny. The same problems also apply to higher taxa at all other ranks under current codes, leading to great taxonomic instability. All proposed objective criteria for determining membership of taxa at a particular rank (e.g., geological age, genetic divergence) are shown to be problematic. In contrast, the clades named by phylogenetic definitions are objective and stable. Node-based and branchbased definitions are most precise; however, apomorphybased definitions can be ambiguous due to difficulty in defining alternative character states, and optimisation uncertainty. A major benefit of ranks (information about relative nesting of taxa) can be achieved even more efficiently using standardised but rankless suffixes already widely used in phylogenetic taxonomy. Finally, in situations where the phylogeny is poorly known, phylogenetic nomenclature appears to be superior to the Linnean system. Phylogenetic nomenclature does not force one to officially name poorly corroborated groupings, whereas Linnean codes compel users to erect and name genera even when relevant supraspecific relationships are poorly known.


EOMYIDS FROM THE RIBESALBES-ALCORA BASIN (EARLY MIOCENE, IBERIAN PENINSULA) AND THEIR BIOSTRATIGRAPHIC AND PALAEOECOLOGICAL IMPLICATIONS.

Abstract: Two species of the family Eomyidae are identified in the Early Miocene localities of the Araia d’Alcora outcrop (Ribesalbes-Alcora Basin, Iberian Peninsula): Ligerimys florancei and Ligerimys ellipticus. The first is rarer than the second, which is one of the most abundant mammals in the Ribesalbes-Alcora Basin assemblages. Due to its abundance, we are able to describe its variability in dental morphology, showing characteristics never previously observed, including the presence of a mesoloph or other features previously described only in ancient assemblages of this species, such as the presence of the anteroloph, which appears in younger assemblages in the Araia sequence. Furthermore, based on the eomyids, we divide the record of the Campisano Ravine section into two long local biozones, depending on the species present. In addition, each local biozone is divided into two smaller sub-biozones, depending on the abundance of each species. We retrospectively compare and correlate the assemblages studied here with other Ligerimys assemblages from the other basins in the Iberian Peninsula. We classify these sites based on the abundance and species of the genus Ligerimys. Additionally, we discuss the palaeoecological preferences of these species

ribesalbes-alcora basin
early miocene
iberian peninsula
ligerimys ellipticus
early aragonian


A bizarre Early Cretaceous enantiornithine bird with unique crural feathers and an ornithuromorph plough-shaped pygostyle

Abstract: Enantiornithes are the most successful clade of Mesozoic birds. Here, we describe a new enantiornithine bird, Cruralispennia multidonta gen. et sp. nov., from the Protopteryx-horizon of the Early Cretaceous Huajiying Formation of China. Despite being among the oldest known enantiornithines, Cruralispennia displays derived morphologies that are unexpected at such an early stage in the evolution of this clade. A plough-shaped pygostyle, like that of the Ornithuromorpha, evolved convergently in the Cruralispennia lineage, highlighting the homoplastic nature of early avian evolution. The extremely slender coracoid morphology was previously unknown among Early Cretaceous enantiornithines but is common in Late Cretaceous taxa, indicating that by 131 million years ago this clade had already experienced considerable morphological differentiation. Cruralispennia preserves unusual crural feathers that are proximally wire-like with filamentous distal tips, a new morphotype previously unknown among fossil or modern feathers, further increasing the known diversity of primitive feather morphologies.

enantiornithine bird
crural feather
plough-shaped pygostyle


The evolutionary history of the extinct ratite moa and New Zealand Neogene paleogeography

Abstract: The ratite moa (Aves: Dinornithiformes) were a speciose group of massive graviportal avian herbivores that dominated the New Zealand (NZ) ecosystem until their extinction ≈600 years ago. The phylogeny and evolutionary history of this morphologically diverse order has remained controversial since their initial description in 1839. We synthesize mitochondrial phylogenetic information from 263 subfossil moa specimens from across NZ with morphological, ecological, and new geological data to create the first comprehensive phylogeny, taxonomy, and evolutionary timeframe for all of the species of an extinct order. We also present an important new geological/paleogeographical model of late Cenozoic NZ, which suggests that terrestrial biota on the North and South Island landmasses were isolated for most of the past 20–30 Ma. The data reveal that the patterns of genetic diversity within and between different moa clades reflect a complex history following a major marine transgression in the Oligocene, affected by marine barriers, tectonic activity, and glacial cycles. Surprisingly, the remarkable morphological radiation of moa appears to have occurred much more recently than previous early Miocene (ca. 15 Ma) estimates, and was coincident with the accelerated uplift of the Southern Alps just ca. 5–8.5 Ma. Together with recent fossil evidence, these data suggest that the recent evolutionary history of nearly all of the iconic NZ terrestrial biota occurred principally on just the South Island.

evolutionary history
ratite moa
moa
terrestrial biota
oligocene


A New Integrated Approach to Taxonomy: The Fusion of Molecular and Morphological Systematics with Type Material in Benthic Foraminifera

Abstract: A robust and consistent taxonomy underpins the use of fossil material in palaeoenvironmental research and long-term assessment of biodiversity. This study presents a new integrated taxonomic protocol for benthic foraminifera by unequivocally reconciling the traditional taxonomic name to a specific genetic type. To implement this protocol, a fragment of the small subunit ribosomal RNA (SSU rRNA) gene is used in combination with 16 quantitative morphometric variables to fully characterise the benthic foraminiferal species concept of Elphidium williamsoni Haynes, 1973. A combination of live contemporary topotypic specimens, original type specimens and specimens of genetic outliers were utilised in this study. Through a series of multivariate statistical tests we illustrate that genetically characterised topotype specimens are morphologically congruent with both the holotype and paratype specimens of E. williamsoni Haynes, 1973. We present the first clear link between morphologically characterised type material and the unique SSU rRNA genetic type of E. williamsoni. This example provides a standard framework for the benthic foraminifera which bridges the current discontinuity between molecular and morphological lines of evidence, allowing integration with the traditional Linnaean roots of nomenclature to offer a new prospect for taxonomic stability.

taxonomy
type material
benthic foraminifera


Bison remains from the Upper Siwaliks of Pakistan

Abstract: Fossil remains ascribed to Bison cf. sivalensis are described in this paper. The material, discovered by the team of Palaeontology of the Punjab University, Lahore, Pakistan during the past few years comes from the Early – Middle Pliocene continental deposits of the Upper Siwaliks (Tatrot Formation, northern Pakistan) dated approximately from 3.3 to 2.6 Ma, and allows interesting comparisons with forms related to the origin of bisons. The new data significantly widens the timedistribution of the species and draws back the first appearance of Bison lineage in the Indian subcontinent.


Pleistocene Hominins as a Resource for Carnivores: A c. 500,000-Year-Old Human Femur Bearing Tooth-Marks in North Africa (Thomas Quarry I, Morocco)

Abstract: In many Middle Pleistocene sites, the co-occurrence of hominins with carnivores, who both contributed to faunal accumulations, suggests competition for resources as well as for living spaces. Despite this, there is very little evidence of direct interaction between them to-date. Recently, a human femoral diaphysis has been recognized in South-West of Casablanca (Morocco), in the locality called Thomas Quarry I. This site is famous for its Middle Pleistocene fossil hominins considered representatives of Homo rhodesiensis. The bone was discovered in Unit 4 of the Grotte à Hominidés (GH), dated to c. 500 ky and was associated with Acheulean artefacts and a rich mammalian fauna. Anatomically, it fits well within the group of known early Middle Pleistocene Homo, but its chief point of interest is that the diaphyseal ends display numerous tooth marks showing that it had been consumed shortly after death by a large carnivore, probably a hyena. This bone represents the first evidence of consumption of human remains by carnivores in the cave. Whether predated or scavenged, this chewed femur indicates that humans were a resource for carnivores, underlining their close relationships during the Middle Pleistocene in Atlantic Morocco.

resource
carnivore
morocco
faunal accumulation
tooth mark


Sea-level rise due to polar ice-sheet mass loss during past warm periods

Abstract: Warming climate, melting ice, rising seas We know that the sea level will rise as climate warms. Nevertheless, accurate projections of how much sea-level rise will occur are difficult to make based solely on modern observations. Determining how ice sheets and sea level have varied in past warm periods can help us better understand how sensitive ice sheets are to higher temperatures. Dutton et al. review recent interdisciplinary progress in understanding this issue, based on data from four different warm intervals over the past 3 million years. Their synthesis provides a clear picture of the progress we have made and the hurdles that still exist. Science, this issue 10.1126/science.aaa4019 Reconstructing past magnitudes, rates, and sources of sea-level rise can help project what our warmer future may hold. BACKGROUND Although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level (GMSL) rise over the last century, mass loss from the Greenland and Antarctic ice sheets is expected to exceed other contributions to GMSL rise under future warming. To better constrain polar ice-sheet response to warmer temperatures, we draw on evidence from interglacial periods in the geologic record that experienced warmer polar temperatures and higher GMSLs than present. Coastal records of sea level from these previous warm periods demonstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales. Inferring GMSL and ice-volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models. ADVANCES Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise. Advances in our understanding of polar ice-sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea-level reconstructions, better ice-sheet constraints, and the recognition that several geophysical processes cause spatially complex patterns in sea level. In particular, accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea-level records and has reconciled a number of site-specific sea-level reconstructions for warm periods that have occurred within the past several hundred thousand years. This enables us to infer that during recent interglacial periods, small increases in global mean temperature and just a few degrees of polar warming relative to the preindustrial period resulted in ≥6 m of GMSL rise. Mantle-driven dynamic topography introduces large uncertainties on longer time scales, affecting reconstructions for time periods such as the Pliocene (~3 million years ago), when atmospheric CO2 was ~400 parts per million (ppm), similar to that of the present. Both modeling and field evidence suggest that polar ice sheets were smaller during this time period, but because dynamic topography can cause tens of meters of vertical displacement at Earth’s surface on million-year time scales and uncertainty in model predictions of this signal are large, it is currently not possible to make a precise estimate of peak GMSL during the Pliocene. OUTLOOK Our present climate is warming to a level associated with significant polar ice-sheet loss in the past, but a number of challenges remain to further constrain ice-sheet sensitivity to climate change using paleo–sea level records. Improving our understanding of rates of GMSL rise due to polar ice-mass loss is perhaps the most societally relevant information the paleorecord can provide, yet robust estimates of rates of GMSL rise associated with polar ice-sheet retreat and/or collapse remain a weakness in existing sea-level reconstructions. Improving existing magnitudes, rates, and sources of GMSL rise will require a better (global) distribution of sea-level reconstructions with high temporal resolution and precise elevations and should include sites close to present and former ice sheets. Translating such sea-level data into a robust GMSL signal demands integration with geophysical models, which in turn can be tested through improved spatial and temporal sampling of coastal records. Further development is needed to refine estimates of past sea level from geochemical proxies. In particular, paired oxygen isotope and Mg/Ca data are currently unable to provide confident, quantitative estimates of peak sea level during these past warm periods. In some GMSL reconstructions, polar ice-sheet retreat is inferred from the total GMSL budget, but identifying the specific ice-sheet sources is currently hindered by limited field evidence at high latitudes. Given the paucity of such data, emerging geochemical and geophysical techniques show promise for identifying the sectors of the ice sheets that were most vulnerable to collapse in the past and perhaps will be again in the future. Peak global mean temperature, atmospheric CO2, maximum global mean sea level (GMSL), and source(s) of meltwater. Light blue shading indicates uncertainty of GMSL maximum. Red pie charts over Greenland and Antarctica denote fraction (not location) of ice retreat. Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo–sea level records.

mass loss
past warm period
sea-level rise


Palaeocopida (Ostracoda) across the Permian–Triassic events: new data from southwestern Taurus (Turkey)

Abstract: The Palaeocopida have been considered as an entirely Palaeozoic group and their disappearance as a marker for the Palaeozoic–Mesozoic boundary. Despite this, 11 Palaeocopida species have been recorded in the Early Triassic. New data obtained in southwestern Taurus at the Permian– Triassic section of Çürük daǧ, permit an assessment of this problem. This paper synthesizes the data on lowermost Triassic ostracodes and revises the youngest Palaecopida occurrences. A new Early Triassic Palaeocopida species is described (Reviya curukensis n. sp.).


Implied weighting and its utility in palaeontological datasets: a study using modelled phylogenetic matrices

Abstract: Implied weighting, a method for phylogenetic inference that actively seeks to downweight supposed homoplasy, has in recent years begun to be widely utilized in palaeontological datasets. Given the method's purported ability at handling widespread homoplasy/convergence, we investigate the effects of implied weighting on modelled phylogenetic data. We generated 100 character matrices consisting of 55 characters each using a Markov Chain morphology model of evolution based on a known phylogenetic tree. Rates of character evolution in these datasets were variable and generated by pulling from a gamma distribution for each character in the matrix. These matrices were then analysed under equal weighting and four settings of implied weights (k = 1, 3, 5, and 10). Our results show that implied weighting is inconsistent in its ability to retrieve a known phylogenetic tree. Equally weighted analyses are found to generally be more conservative, retrieving higher frequency of polytomies but being less likely to generate erroneous topologies. Implied weighting is found to generally resolve polytomies while also propagating errors, resulting in an increase in both correctly and incorrectly resolved nodes with a tendency towards higher rates of error compared to equal weighting. Our results suggest that equal weights may be a preferable method for parsimony analysis.

weighting
palaeontological dataset
matrix


Shuidonggou localities 1 and 2 in northern China: archaeology and chronology of the Initial Upper Palaeolithic in north-east Asia

Abstract: Shuidonggou localities 1 and 2 provide key evidence for the Initial Upper Palaeolithic of north-east Asia. In a recent article in Antiquity (87 (2013), 368–383), Li et al. proposed a new chronology, building on the earlier results of Madsen et al. (Antiquity 75 (2001), 705–716). Here Susan Keates and Yaroslav Kuzmin take issue with the new chronology. The article is followed by a response from Li and Gao.

initial upper palaeolithic
north-east asia
shuidonggou locality


Basal paravian functional anatomy illuminated by high-detail body outline

Abstract: Body shape is a fundamental expression of organismal biology, but its quantitative reconstruction in fossil vertebrates is rare. Due to the absence of fossilized soft tissue evidence, the functional consequences of basal paravian body shape and its implications for the origins of avians and flight are not yet fully understood. Here we reconstruct the quantitative body outline of a fossil paravian Anchiornis based on high-definition images of soft tissues revealed by laser-stimulated fluorescence. This body outline confirms patagia-bearing arms, drumstick-shaped legs and a slender tail, features that were probably widespread among paravians. Finely preserved details also reveal similarities in propatagial and footpad form between basal paravians and modern birds, extending their record to the Late Jurassic. The body outline and soft tissue details suggest significant functional decoupling between the legs and tail in at least some basal paravians. The number of seemingly modern propatagial traits hint that feathering was a significant factor in how basal paravians utilized arm, leg and tail function for aerodynamic benefit.


The pharynx of the stem-chondrichthyan Ptomacanthus and the early evolution of the gnathostome gill skeleton

Abstract: The gill apparatus of gnathostomes (jawed vertebrates) is fundamental to feeding and ventilation and a focal point of classic hypotheses on the origin of jaws and paired appendages. The gill skeletons of chondrichthyans (sharks, batoids, chimaeras) have often been assumed to reflect ancestral states. However, only a handful of early chondrichthyan gill skeletons are known and palaeontological work is increasingly challenging other pre-supposed shark-like aspects of ancestral gnathostomes. Here we use computed tomography scanning to image the three-dimensionally preserved branchial apparatus in Ptomacanthus, a 415 million year old stem-chondrichthyan. Ptomacanthus had an osteichthyan-like compact pharynx with a bony operculum helping constrain the origin of an elongate elasmobranch-like pharynx to the chondrichthyan stem-group, rather than it representing an ancestral condition of the crown-group. A mixture of chondrichthyan-like and plesiomorphic pharyngeal patterning in Ptomacanthus challenges the idea that the ancestral gnathostome pharynx conformed to a morphologically complete ancestral type.

pharynx
ptomacanthus
gnathostome
jawed vertebrate
chondrichthyan


Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits

Abstract: The ca. 3.48 Ga Dresser Formation, Pilbara Craton, Western Australia, is well known for hosting some of Earth's earliest convincing evidence of life (stromatolites, fractionated sulfur/carbon isotopes, microfossils) within a dynamic, low-eruptive volcanic caldera affected by voluminous hydrothermal fluid circulation. However, missing from the caldera model were surface manifestations of the volcanic-hydrothermal system (hot springs, geysers) and their unequivocal link with life. Here we present new discoveries of hot spring deposits including geyserite, sinter terracettes and mineralized remnants of hot spring pools/vents, all of which preserve a suite of microbial biosignatures indicative of the earliest life on land. These include stromatolites, newly observed microbial palisade fabric and gas bubbles preserved in inferred mineralized, exopolymeric substance. These findings extend the known geological record of inhabited terrestrial hot springs on Earth by B3 billion years and offer an analogue in the search for potential fossil life in ancient Martian hot springs.

land
volcanic caldera
palisade fabric
terrestrial hot spring


Carbon and nitrogen stable isotopes as tracers of change in diet breadth during Middle and Upper Palaeolithic in Europe

Abstract: Carbon and nitrogen stable isotope ratios in fossil bone collagen have been used as evidence for an increase of diet breadth between Middle Palaeolithic Neanderthals and Early Upper Palaeolithic anatomically modern humans. In this paper, we revisit the rules of palaeodietary reconstruction using collagen stable isotopes and reassess the possible isotopic signatures of potential protein resources available to prehistoric humans. It appears that the interpretation of the human's isotopic signature does not necessarily imply a significant proportion of aquatic-derived protein in the diet neither for Neandertal nor for first anatomically modern humans in Europe. Exploitation of aquatic ecosystems by humans needs to be supported by further zooarchaeological evidence. Nevertheless, isotopic biogeochemistry of fossil human collagen can be very useful in palaeodietary reconstructions provided that basic rules are followed while selecting samples of coeval fauna, in order to establish the end members of different food resources. Significant progress investigating the evolution of subsistence strategies in fossil hominids is expected from a combination of zooarchaeological and isotopic data. Copyright © 2004 John Wiley & Sons, Ltd.


Postcranial anatomy of Pissarrachampsa sera (Crocodyliformes, Baurusuchidae) from the Late Cretaceous of Brazil: insights on lifestyle and phylogenetic significance

Abstract: The postcranial anatomy of Crocodyliformes has historically been neglected, as most descriptions are based solely on skulls. Yet, the significance of the postcranium in crocodyliforms evolution is reflected in the great lifestyle diversity exhibited by the group, with members ranging from terrestrial animals to semi-aquatic and fully marine forms. Recently, studies have emphasized the importance of the postcranium. Following this trend, here we present a detailed description of the postcranial elements of Pissarrachampsa sera (Mesoeucrocodylia, Baurusuchidae), from the Adamantina Formation (Bauru Group, Late Cretaceous of Brazil). The preserved elements include dorsal vertebrae, partial forelimb, pelvic girdle, and hindlimbs. Comparisons with the postcranial anatomy of baurusuchids and other crocodyliforms, together with body-size and mass estimates, lead to a better understanding of the paleobiology of Pissarrachampsa sera, including its terrestrial lifestyle and its role as a top predator. Furthermore, the complete absence of osteoderms in P. sera, a condition previously known only in marine crocodyliforms, suggests osteoderms very likely played a minor role in locomotion of baurusuchids, unlike other groups of terrestrial crocodyliforms. Finally, a phylogenetic analysis including the newly recognized postcranial features was carried out, and exploratory analyses were performed to investigate the influence of both cranial and postcranial characters in the phylogeny of Crocodyliformes. Our results suggest that crocodyliform relationships are mainly determined by cranial characters. However, this seems to be a consequence of the great number of missing entries in the data set with only postcranial characters and not of the lack of potential (or synapomorphies) for this kind of data to reflect the evolutionary history of Crocodyliformes.

crocodyliformes
baurusuchidae
postcranial anatomy


Abstract: Louys, J., 23.3.2015. Wombats (Vombatidae: Marsupialia) from the Pliocene Chinchilla Sand, southeast Queensland, Australia. Alcheringa 39, XXX–XXX. ISSN 0311-5518 The Chinchilla Local Fauna is one of the richest Pliocene vertebrate fossil assemblages in Australia. However, Vombatidae material preserved in the Chinchilla Sand is very poorly known, and no systematic examination of the wombats from Chinchilla has been conducted. Here I review the cranio-dental and mandibular wombat remains derived from Chinchilla. This material includes both adults and pouch-young specimens. At least five species of wombats are preserved in the fluviatile Chinchilla deposits, although a lack of stratigraphically controlled excavations makes it impossible to determine whether all five species were sympatric. Several wombat taxa are revised: Sedophascolomys gen. nov. is formally erected to replace the invalid ‘Phascolomys’; Vombatus mitchelli (Owen) is recognized as a species distinct from Vombatus ursinus (Shaw), and is recorded for the first time from Chinchilla. In addition to Vombatus mitchelli, the Chinchilla Sand also preserves evidence of Phascolonus gigas, Ramsayia magna, Ramsayia lemleyi and Sedophascolomys medius. Julien Louys [julien.louys@anu.edu.au], Department of Archaeology and Natural History, School of Culture, History, and Languages, ANU College of Asia and the Pacific, The Australian National University, Canberra, ACT 2601, Australia.

vombatidae
marsupialia
pliocene chinchilla sand


A long-tailed marine reptile from China provides new insights into the Middle Triassic pachypleurosaur radiation

Abstract: Pachypleurosaurs (Pachypleurosauroidea) are a group of small to medium-sized, lizard-like marine reptiles in the Early to Middle Triassic, including Pachypleurosauridae, Keichousauridae and closely related taxa. The group is generally considered as a sauropterygian radiation, but its phylogenetic interrelationships remain highly debated. Here, we present a new pachypleurosaurid, Honghesaurus longicaudalis gen. et sp. nov., from the early Middle Triassic (Anisian, ~ 244 Ma) marine deposits in Luxi, Yunnan, China. The discovery documents the first really long-tailed pachypleurosaur with totally 121 (69 caudal) vertebrae, providing new evidence for the vertebral multiplication and ecological adaption of this group. The long trunk associated with an incredibly long tail could provide Honghesaurus the advantage of maneuverability and energy efficiency for lateral undulatory swimming. Honghesaurus, although possessing a series of autapomorphies, fills the morphological gap between Qianxisaurus from the Ladinian Xingyi Biota and Wumengosaurus from the Anisian Panxian Biota. Phylogenetic studies unite these three pachypleurosaurids as a monophyletic clade above European pachypleurosaurid clades and provide new insights into the interrelationships of this group. Our scenario of pachypleurosaurian phylogeny combined with the stratigraphic data imply that the Tethys Ocean was a west–east corridor for dispersal of pachypleurosaurids from Europe into South China.

marine reptile
china
new insight
pachypleurosaur
honghesaurus


Evidence for Neandertal Jewelry: Modified White-Tailed Eagle Claws at Krapina

Abstract: We describe eight, mostly complete white-tailed eagle (Haliaëtus [Haliaeetus] albicilla) talons from the Krapina Neandertal site in present-day Croatia, dating to approximately 130 kyrs ago. Four talons bear multiple, edge-smoothed cut marks; eight show polishing facets and/or abrasion. Three of the largest talons have small notches at roughly the same place along the plantar surface, interrupting the proximal margin of the talon blade. These features suggest they were part of a jewelry assemblage, --- the manipulations a consequence of mounting the talons in a necklace or bracelet. An associated phalanx articulates with one of the talons and has numerous cut marks, some of which are smoothed. These white-tailed eagle bones, discovered more than 100 years ago, all derive from a single level at Krapina and represent more talons than found in the entire European Mousterian period. Presence of eight talons indicates that the Krapina Neandertals acquired and curated eagle talons for some kind of symbolic purpose. Some have argued that Neandertals lacked symbolic ability or copied this behavior from modern humans. These remains clearly show that the Krapina Neandertals made jewelry well before the appearance of modern humans in Europe, extending ornament production and symbolic activity early into the European Mousterian.

krapina
phalanx
eagle talon
symbolic purpose


Scenes from the past: radiologic evidence of anthropogenic mummification in the Capuchin Catacombs of Palermo, Sicily.

Abstract: The purpose of this study was to use paleoradiologic analyses to investigate a sample of the mummies in the Capuchin Catacombs in Palermo, Sicily, in order to assess skeletal abnormalities and the state of preservation, especially the condition of the internal organs, and to determine radiologic evidence of anthropogenic mummification. Ten 19th and early 20th century mummies with good external preservation were investigated by using a portable direct radiography unit inside the Capuchin Catacombs. The radiographs clearly demonstrated signs of anthropogenic mummification in nine of the 10 mummies investigated. The embalming methods that had been used included (a) evisceration and arterial injection; (b) the placement of foreign materials into the orbits and the nasal and oral cavities; and (c) filling of the thoracic, abdominal, and rectal cavities with foreign materials. Organ preservation varied greatly among the mummies, although brain tissue was found in all of the mummies. Analyses of the skeletal material of the mummies showed evidence of healed vertebral fractures, age-related degenerative changes, and, in one of the child mummies, a remarkable skeletal pathologic condition. The radiographs clearly illustrated different methods of anthropogenic mummification in the catacomb mummies of Palermo, allowed assessment of the preservation of the mummies, and demonstrated skeletal abnormalities.

radiologic evidence
anthropogenic mummification
oral cavity
thoracic


Lateral arm plate morphology in brittle stars (Echinodermata: Ophiuroidea): new perspectives for ophiuroid micropalaeontology and classification

Abstract: Lateral arm plates, the spine-bearing plates of the ophiuroid arm skeleton, have long been assumed to display sufficient morphological diversity to be used for species identifications in ophiuroid micropalaeontology. As a consequence, many new brittle-star species have been described on the basis of isolated fossil lateral arm plates. A substantial lack of information on the morphological variability of lateral arm plates in respect of taxon concepts, however, has led to increasing confusion over species limits and excessive extensions of stratigraphic species ranges. In this study, we therefore performed a detailed assessment of the variability of lateral arm plate morphology within and between species in order to test to what extent isolated lateral arm plates can be used for species identifications. To this end, we investigated the morphological variability of lateral arm plates within species according to ontogenetic changes and according to the position of the plates along the arm. Furthermore, we examined the lateral arm plates of 56 Recent species, belonging to 27 genera and 10 families, and systematically assessed their morphology in the light of currently accepted taxon concepts. The results of this study demonstrate that lateral arm plate morphology is in accordance with most family, genus and species limits. Some of the currently accepted taxon concepts, including the affinities between the Ophiacanthidae and Ophiocomidae, however, are challenged by lateral arm plate morphology. Differences in lateral arm plate morphology between taxa are the most conspicuously displayed by adult proximal lateral arm plates, as a consequence of their high degree of differentiation compared to distal or juvenile lateral arm plates. Differences at species level, often pertain to characters which were considered to be within-species variation in previous micropalaeontological works, suggests that species identifications based on isolated fossil lateral arm plates require a much more detailed and careful morphological assessment. Some of the species studied herein displayed indistinguishable lateral arm plate morphologies, but belonged to the same genus in all cases. Our study endorses the use of isolated fossil lateral arm plates for taxonomic interpretations in ophiuroid micropalaeontology, including species identifications and the creation of new taxa, providing that descriptions are based on pristinely preserved adult proximal LAPs, described and illustrated using SEM-pictures of both the external and internal sides of the plate.

arm plate morphology
brittle star
ophiuroid micropalaeontology


Giant Mesozoic coelacanths (Osteichthyes, Actinistia) reveal high body size disparity decoupled from taxic diversity

Abstract: The positive correlation between speciation rates and morphological evolution expressed by body size is a macroevolutionary trait of vertebrates. Although taxic diversification and morphological evolution are slow in coelacanths, their fossil record indicates that large and small species coexisted, which calls into question the link between morphological and body size disparities. Here, we describe and reassess fossils of giant coelacanths. Two genera reached up to 5 m long, placing them among the ten largest bony fish that ever lived. The disparity in body size adjusted to taxic diversity is much greater in coelacanths than in ray-finned fishes. Previous studies have shown that rates of speciation and rates of morphological evolution are overall low in this group, and our results indicate that these parameters are decoupled from the disparity in body size in coelacanths. Genomic and physiological characteristics of the extant Latimeria may reflect how the extinct relatives grew to such a large size. These characteristics highlight new evolutionary traits specific to these “living fossils”.

coelacanth
body size disparity
taxic diversity
ray-finned fish


Gradual decline in mobility with the adoption of food production in Europe

Abstract: Significance Declining mobility levels following the Pleistocene had profound effects on human demography, social organization, and health, but the exact timing and pace of this critical change are unknown. Here we examine direct evidence for changing mobility levels from limb bone structural characteristics in a large sample of European skeletons spanning the past 30,000 y. Our results show that mobility first declined during the Neolithic, at the onset of food production, but that the decline was gradual, continuing for several thousand years as agriculture intensified. No change in relative limb strength occurred during the past 2,000 y. Thus, the more gracile modern human skeleton is a result of increased sedentism tied to food production, not subsequent mechanization and industrialization. Increased sedentism during the Holocene has been proposed as a major cause of decreased skeletal robusticity (bone strength relative to body size) in modern humans. When and why declining mobility occurred has profound implications for reconstructing past population history and health, but it has proven difficult to characterize archaeologically. In this study we evaluate temporal trends in relative strength of the upper and lower limb bones in a sample of 1,842 individuals from across Europe extending from the Upper Paleolithic [11,000–33,000 calibrated years (Cal y) B.P.] through the 20th century. A large decline in anteroposterior bending strength of the femur and tibia occurs beginning in the Neolithic (∼4,000–7,000 Cal y B.P.) and continues through the Iron/Roman period (∼2,000 Cal y B.P.), with no subsequent directional change. Declines in mediolateral bending strength of the lower limb bones and strength of the humerus are much smaller and less consistent. Together these results strongly implicate declining mobility as the specific behavioral factor underlying these changes. Mobility levels first declined at the onset of food production, but the transition to a more sedentary lifestyle was gradual, extending through later agricultural intensification. This finding only partially supports models that tie increased sedentism to a relatively abrupt Neolithic Demographic Transition in Europe. The lack of subsequent change in relative bone strength indicates that increasing mechanization and urbanization had only relatively small effects on skeletal robusticity, suggesting that moderate changes in activity level are not sufficient stimuli for bone deposition or resorption.


Innovatiocaris
 , a complete radiodont from the early Cambrian Chengjiang Lagerstätte and its implications for the phylogeny of Radiodonta

Abstract:
 The Palaeozoic radiodonts are important for understanding the evolution and ecology of early euarthropods. However, complete radiodont fossils are very rare, despite their central roles in understanding radiodont palaeobiology. Here we describe
 Innovatiocaris maotianshanensis
 gen. et sp. nov. in detail based on an iconic complete radiodont specimen from the early Cambrian Chengjiang Lagerstätte of China. The head of
 I
 .
 maotianshanensis
 has a pair of stalked eyes, an ovate dorsal sclerite, a pair of frontal appendages composed of 11 distal articulated podomeres bearing spiky endites with only anterior auxiliary spines, and a putative triradial oral cone. The body possesses six anterior pairs of small differentiated neck flaps and ten posterior pairs of trunk flaps, with soft tissues including alimentary canal and musculature preserved. The tail includes a tail fan comprising three pairs of lateral blades and a pair of very long furcae. Another two new species,
 Innovatiocaris
 ? sp. and
 I
 .?
 multispiniformis
 sp. nov., are established based on the frontal appendages with different numbers of anterior auxiliary spines and are tentatively assigned to
 Innovatiocaris
 . Phylogenetic analysis retrieves
 Innovatiocaris
 as either a basal member of Hurdiidae or early-branching species of the non-hurdiid clade. Thus,
 Innovatiocaris
 provides new insights into the radiodont phylogeny and illuminates the early diversification of Radiodonta.

 Supplementary material:
 Supplementary figures, phylogenetic data matrix, and a character list for phylogenetic analysis are available at
 https://doi.org/10.6084/m9.figshare.c.6179300

 Thematic collection:
 This article is part of the Advances in the Cambrian Explosion collection available at:
 https://www.lyellcollection.org/topic/collections/advances-in-the-cambrian-explosion

radiodont
cambrian chengjiang lagerstätte
euarthropod
phylogenetic analysis


Nematode larvae in fossilized animal coprolites from lower and middle Pleistocene sites, central Italy.

Abstract: Nematode larvae were found in mineralized animal coprolites collected in lower and middle Pleistocene sites, central Italy. Coprolites collected in 4 paleontological sites dated from 1.5 million years to 30,000 years ago were identified as of Hyaenidae (Mammalia, Carnivora). Checklists available for present-day Hyaenidae did not permit identification of the larvae found. This is one of the most ancient parasite findings in coprolites.

animal coprolite
middle pleistocene site
nematode larvae


Bone histology, palaeobiology, and early diagenetic history of extinct equids from Turkey

Abstract: Abstract Bone histology has proved to be a valuable tool to obtain information about the palaeobiology and early taphonomic history of fossil vertebrates. However, there are still many extinct taxa for which bone histology studies could be applied to deduce information about their life history and early diagenetic changes. Here, we partially fill this gap by studying bone microstructure and bone micropreservation in the third metapodia of Hipparion and Equus recovered from several Miocene, Pliocene, and Pleistocene localities in Turkey. Our histological analysis reveals that most of the bone cortices under study are composed of a well-vascularized fibrolamellar bone. Furthermore, we record the presence of compact coarse cancellous bone in a Hipparion metatarsal. In terms of histological preservation, our findings provide supporting evidence that differences in moisture, oxygen, and/or temperature during fossilisation at the different localities impacted the quality of bone preservation. Bacterial bioerosion was extensive in the samples, and we also identified a specific tunnelling morphology that we tentatively consider to be damage caused by freshwater algae. The present study provides novel insight into the palaeobiology and early diagenetic history of extinct horses from Turkey and sets the stage for further research in this area.

palaeobiology
early diagenetic history
turkey


Glacial fluctuations of the Indian monsoon and their relationship with North Atlantic climate: new data and modelling experiments

Abstract: Abstract. Several paleoclimate records such as from Chinese loess, speleothems or upwelling indicators in marine sediments present large variations of the Asian monsoon system during the last glaciation. Here, we present a new record from the northern Andaman Sea (core MD77-176) which shows the variations of the hydrological cycle of the Bay of Bengal. The high-resolution record of surface water δ18O dominantly reflects salinity changes and displays large millennial-scale oscillations over the period 40 000 to 11 000 yr BP. Their timing and sequence suggests that events of high (resp. low) salinity in the Bay of Bengal, i.e. weak (resp. strong) Indian monsoon, correspond to cold (resp. warm) events in the North Atlantic and Arctic, as documented by the Greenland ice core record. We use the IPSL_CM4 Atmosphere-Ocean coupled General Circulation Model to study the processes that could explain the teleconnection between the Indian monsoon and the North Atlantic climate. We first analyse a numerical experiment in which such a rapid event in the North Atlantic is obtained under glacial conditions by increasing the freshwater flux in the North Atlantic, which results in a reduction of the intensity of the Atlantic meridional overturning circulation. This freshwater hosing results in a weakening of the Indian monsoon rainfall and circulation. The changes in the continental runoff and local hydrological cycle are responsible for an increase in salinity in the Bay of Bengal. This therefore compares favourably with the new sea water δ18O record presented here and the hypothesis of synchronous cold North Atlantic and weak Indian monsoon events. Additional sensitivity experiments are produced with the LMDZ atmospheric model to analyse the teleconnection mechanisms between the North Atlantic and the Indian monsoon. The changes over the tropical Atlantic are shown to be essential in triggering perturbations of the subtropical jet over Africa and Eurasia, that in turn affect the intensity of the Indian monsoon. These relationships are also found to be valid in additional coupled model simulations in which the Atlantic meridional overturning circulation (AMOC) is forced to resume.

fluctuation
monsoon
north atlantic climate


Increase in metazoan ecosystem engineering prior to the Ediacaran–Cambrian boundary in the Nama Group, Namibia

Abstract: The disappearance of the soft-bodied Ediacara biota at the Ediacaran–Cambrian boundary potentially represents the earliest mass extinction of complex life, although the precise driver(s) of this extinction remain unresolved. The ‘biotic replacement’ model proposes that an evolutionary radiation of metazoan ecosystem engineers in the latest Ediacaran profoundly altered marine palaeoenvironments, resulting in the extinction of Ediacara biota and setting the stage for the subsequent Cambrian Explosion. However, metazoan ecosystem engineering across the Ediacaran–Cambrian transition has yet to be quantified. Here, we test this key tenet of the biotic replacement model by characterizing the intensity of metazoan bioturbation and ecosystem engineering in trace fossil assemblages throughout the latest Ediacaran Nama Group in southern Namibia. The results illustrate a dramatic increase in both bioturbation and ecosystem engineering intensity in the latest Ediacaran, prior to the Cambrian boundary. Moreover, our analyses demonstrate that the highest-impact ecosystem engineering behaviours were present well before the onset of the Cambrian. These data provide the first support for a fundamental prediction of the biotic replacement model, and evidence for a direct link between the early evolution of ecosystem engineering and the extinction of the Ediacara biota.

metazoan ecosystem engineering
ediacaran–cambrian boundary
namibia


New superfamily and three new families of tetraodontiform fishes from the Upper Cretaceous : the earliest and most morphologically primitive plectognaths

Abstract: Tyler, James C , and Lorenzo Sorbini. New Superfamily and Three New Families of Tetraodontiform Fishes from the Upper Cretaceous: The Earliest and Most Morphologically Primitive Plectognaths. Smithsonian Contributions to Paleobiology, number 82, 59 pages, 25 figures, 2 tables, 1996.—Fishes of the order Tetraodontiformes previously have been known with assurance from as early as the Lower Eocene, about 55 MYA. Two Upper Cretaceous taxa, Protriacanthus d'Erasmo (1946) from Comen, Slovenia, about 90 MYA, and Plectocretacicus Sorbini (1979) from Hakel, Lebanon, about 95 MYA, were referred by their authors to the tetraodontiforms, respectively in the vicinity of triacanthoids and ostracioids. Both of these taxa were originally based on single specimens in which insufficient details of critical osteological features were exposed, and their familial and ordinal placement were open to question. Based on additional specimens now available, including acid preparations of several specimens of both species, we believe that they represent two new families (Protriacanthidae and Plectocretacicidae) of tetraodontiforms with numerous features that are more primitive than previously reported for the order. We describe a third taxon, the new genus Cretatriacanthus (and new family Cretatriacanthidae), based on a single specimen from the Upper Cretaceous of Nardd, Italy, about 70 MYA. It shares most of the numerous primitive features of Protriacanthus and Plectocretacicus. Although many of their features are primitive, all three of these Upper Cretaceous taxa possess the most salient derived features of tetraodontiforms (e.g., reduced number of vertebrae, no anal-fin spines, reduced number of pelvic-fin rays, absence of certain skull bones, and, when present, long posterior process of pelvis with its halves in close contact or fused). The three Upper Cretaceous taxa share four derived features (absence of teeth, modified scales around base of pelvic spine, presence of subocular shelf, and diminutive size) that unite them in a clade herein recognized as the superfamily Plectocretacicoidea, whereas all other tetraodontiforms (those from the Lower Eocene to present) are united by seven derived features. Within the Plectocretacicoidea, five derived features support the sister-group relationship of Protriacanthus and Plectocretacicus. Each of the three Upper Cretaceous taxa has a mosaic of primitive and specialized features, with some of the latter being independently derived relative to similar features of triacanthoids, balistoids, and ostracioids. The evidence indicates that the Plectocretacicoidea (presently known from 70 to 95 MYA) are the morphologically primitive sister group of all other tetraodontiforms (presently known from 55 MYA to Recent). OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The trilobite Phaecops rana Green. Library of Congress Cataloging-in-Publication Data Tyler, James C , 1935New superfamily and three new families of tetraodontiform fishes from the Upper Cretaceous . the earliest and most morphologically primitive plectognaths / James C. Tyler and Lorenzo Sorbini. p. cm. — (Smithsonian contributions to paleobiology ; no. 82) Includes bibliographical references. 1. Cretatriacanthus guidotti. 2. Plectocretacicus clarae. 3. Protriacanthus gortanii. 4. Paleontology— Cretaceous. 5. Fishes, Fossil. I. Sorbini, Lorenzo. II. Title. III. Series. QE701.S56 no. 82 [QE852.T48] 560 s—dc20 [567\5] 95-46251 © The paper used in this publication meets the minimum requirements of the American National Standard for Permanence of Paper for Printed Library Materials Z39.48—1984.

new family
tetraodontiform fish
primitive plectognath


Abstract: Filippini, F.S., Otero, A. & Gasparini, Z., June 2016. The phylogenetic relevance of the sacrum among macronarian sauropods: insights from a pelvis from the Upper Cretaceous of Patagonia, Argentina. Alcheringa 41, xxx–xxx. ISSN 0311-5518. Anatomical variation in the sacrum is useful for differentiating sauropod lineages. Morphological variation in the sacrum has been underestimated mainly because of its anatomical complexity and uncertain homologies with presacral and postsacral elements. We describe a titanosaurian sauropod pelvis (MLP 46-VIII-21-2) from Plottier (Neuquén Province, Argentina) collected in the 1940s from Coniacian–Santonian (Upper Cretaceous) strata. The degree of bone fusion in the specimen (fused vertebral centra forming a single rod, with neural arches fused to the corresponding centrum and to adjacent neural arches) indicates a late ontogenetic age. The presence of a space between the first vertebra and the anterior margin of the illium, together with a scar located on the anterior part of the preactabular process, suggest the possible presence of a sixth sacral vertebra (putative dorsosacral additional characters present in the ilium point towards affinities with Titanosauria. The completeness and good preservation of the specimen allowed us to track features along the sacral series and to compare characters with other sauropods. Within a phylogenetic context, and based on the pattern present in basal sauropodomorphs, the presence of three sacral elements attached to the rim of the acetabulum in eusauropods opens the possibility for considering such elements as primordial sacrals. Florencia S. Filippini [florencia304@live.com.ar], División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, La Plata, 1900, Bs. As., Argentina; Alejandro Otero [alexandros.otero@gmail.com]; Zulma Gasparini [zgaspari@fcnym.unlp.edu.ar] CONICET—División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, La Plata, 1900, Bs. As., Argentina.

phylogenetic relevance
sacrum
macronarian sauropod


Mylodon darwini Owen (Xenarthra, Mylodontinae) from the Late Pleistocene of Mesopotamia, Argentina, with Remarks on Individual Variability, Paleobiology, Paleobiogeography, and Paleoenvironment

Abstract: ABSTRACT The subfamily Mylodontinae, typified by Mylodon, is known from the Colloncuran (late Miocene of Patagonia, Argentina) to the late Pleistocene of South America and North America. Mylodontinae have been recorded during the Pleistocene of Argentina, including the genera Glossotherium, Paraglossotherium, Lestodon, and Mylodon, with Paraglossotherium and Mylodon not as well known as the other genera. In Argentina there have been traditionally four species of Mylodon, M. darwini, M. zeballozi, M. listai, and M. insigne, although the validity of some has been considered doubtful. A nearly complete skull with an associated mandible of Mylodon darwini from the late Pleistocene of Mesopotamia, Argentina, is described. The specimen represents the first record of the species in the Mesopotamian region. The morphometric analysis indicates that M. darwini had greater individual variability than previously thought. Although based on the results of the morphologic and morphometric analysis, the idea of sexual dimorphism for M. darwini is, for the time being, unwarranted. This new record also supports the idea that Mylodon had great ecological tolerance and was capable of inhabiting climates ranging from cold and arid to warm and humid, and even montane environments.

mylodontinae
late pleistocene
mesopotamia


Origins and genetic legacy of prehistoric dogs

Abstract: Dog domestication was multifaceted Dogs were the first domesticated animal, likely originating from human-associated wolves, but their origin remains unclear. Bergstrom et al. sequenced 27 ancient dog genomes from multiple locations near to and corresponding in time to comparable human ancient DNA sites (see the Perspective by Pavlidis and Somel). By analyzing these genomes, along with other ancient and modern dog genomes, the authors found that dogs likely arose once from a now-extinct wolf population. They also found that at least five different dog populations ∼10,000 years before the present show replacement in Europe at later dates. Furthermore, some dog population genetics are similar to those of humans, whereas others differ, inferring a complex ancestral history for humanity's best friend. Science, this issue p. 557; see also p. 522 Ancient dog genomes elucidate diversification and a complex genetic history relative to that of humans. Dogs were the first domestic animal, but little is known about their population history and to what extent it was linked to humans. We sequenced 27 ancient dog genomes and found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. By 11,000 years ago, at least five major ancestry lineages had diversified, demonstrating a deep genetic history of dogs during the Paleolithic. Coanalysis with human genomes reveals aspects of dog population history that mirror humans, including Levant-related ancestry in Africa and early agricultural Europe. Other aspects differ, including the impacts of steppe pastoralist expansions in West and East Eurasia and a near-complete turnover of Neolithic European dog ancestry.

dog domestication wolf ancestry paleolithic


Schischcatella (Fenestrata, Bryozoa) from the Devonian of the Rhenish Massif, Germany

Abstract: Abstract:  The Devonian fenestrate bryozoan, Schischcatella Waschurova, 1964 , possessed colonies in the form of low, erect bifoliate fronds that grew from an encrusting sheet‐like base with autozooecia arranged in biserial, bifurcating rows. This growth habit is unique in fenestrates, which normally had unilaminate arborescent colonies. Originally, Schischcatella was described from the Lower Devonian of Tajikistan. This article describes a new species, S. heinorum sp. nov., from the Middle Devonian of the Eifel (western Rhenish Massif, Germany) with additional material from the Lower Devonian of the Kellerwald (eastern Rhenish Massif, Germany). External and internal morphologies of this bryozoan have been studied using abundant material. The growth habit of Schischcatella suggests a completely different pattern of feeding currents than that in the normal fenestrate colony. The outflow of the filtered water occurred only on edges of colonies between rami. In the absence of chimneys (areas of vertical water expelling), such a functional morphology may have restricted extension of the colony in a distal direction. The evolution of Schischcatella is apparently an example of paedomorphosis, the genus evolved from an unknown semicosciniid species by the early ontogenetic interruption of colony development and further changes in the mode of growth.


Morphology and developmental traits of the trilobite Changaspis elongata from the Cambrian Series 2 of Guizhou, South China

Abstract: The morphology and ontogeny of the trilobite Changaspis elongata based on 216 specimens collected from the Lazizhai section of the Balang Formation (Stage 4, Series 2 of the Cambrian) in Guizhou Province, South China are described. The relatively continuous ontogenetic series reveals morphological changes, and shows that the species has seventeen thoracic segments in the holaspid period, instead of the sixteen as previously suggested. The development of the pygidial segments shows that their number gradually decreases during ontogeny. A new dataset of well-preserved specimens offers a unique opportunity to investigate developmental traits after segment addition is completed. The ontogenetic size progressions for the lengths of cephalon and trunk show overall compliance with Dyar’s rule. As a result of different average growth rates for the lengths of cephalon, trunk and pygidium, the length of the thorax relative to the body shows a gradually increasing trend; however, the cephalon and pygidium follow the opposite trend. Morphometric analysis across fourteen post-embryonic stages reveals growth gradients with increasing values for each thoracic segment from anterior to posterior. The reconstruction of the development traits shows visualization of the changes in relative growth and segmentation for the different body parts. The new dataset and growth gradient of the trunk suggest that the thoracic segment growth dynamics of early Cambrian to Silurian trilobites follow the same general continuous, steady-state growth gradient decreasing from posterior to anterior.

developmental trait
changaspis elongata
morphology


Large-scale hydrological change drove the late Miocene C4 plant expansion in the Himalayan foreland and Arabian Peninsula

Abstract: Carbon isotope changes in paleosols from Siwalik, Pakistan, and marine sediments from the Bengal Fan indicate a major C 4 plant expansion in the Himalayan foreland during the late Miocene. However, the timing and mechanisms behind the C 4 plant expansion remain enigmatic. Here we present high-resolution (∼60 k.y.) biomarker and compound-specific isotope data spanning the past 11 m.y. from Ocean Drilling Program Site 722 in the Arabian Sea. An ∼5‰–6‰ increase in leaf wax δ 13 C values indicates a marked rise of C 4 plants from 10 to 5.5 Ma, with accelerated expansion from 7.9 to 5.5 Ma. A concurrent ∼50‰ rise in leaf wax δD values is attributed to a combined effect of changes in precipitation amount and evaporation, indicating that source regions for the plant waxes became progressively drier from 10 to 5.5 Ma. In contrast to earlier reports, our isotope records, biomarker abundances, alkenone U K′ 37 , and Globigerina bulloides abundance data do not suggest enhanced summer monsoon circulation during this time interval. Rather, our results suggest that large-scale hydrological changes drove the late Miocene expansion of C 4 plants in the Himalayan foreland and Arabian Peninsula.

foreland
arabian peninsula
large-scale hydrological change


Evolution and Consequences of Endothermy in Fishes

Abstract: Regional endothermy, the conservation of metabolic heat by vascular countercurrent heat exchangers to elevate the temperature of the slow‐twitch locomotor muscle, eyes and brain, or viscera, has evolved independently among several fish lineages, including lamnid sharks, billfishes, and tunas. All are large, active, pelagic species with high energy demands that undertake long‐distance migrations and move vertically within the water column, thereby encountering a range of water temperatures. After summarizing the occurrence of endothermy among fishes, the evidence for two hypothesized advantages of endothermy in fishes, thermal niche expansion and enhancement of aerobic swimming performance, is analyzed using phylogenetic comparisons between endothermic fishes and their ectothermic relatives. Thermal niche expansion is supported by mapping endothermic characters onto phylogenies and by combining information about the thermal niche of extant species, the fossil record, and paleoceanographic conditions during the time that endothermic fishes radiated. However, it is difficult to show that endothermy was required for niche expansion, and adaptations other than endothermy are necessary for repeated diving below the thermocline. Although the convergent evolution of the ability to elevate slow‐twitch, oxidative locomotor muscle temperatures suggests a selective advantage for that trait, comparisons of tunas and their ectothermic sister species (mackerels and bonitos) provide no direct support of the hypothesis that endothermy results in increased aerobic swimming speeds, slow‐oxidative muscle power, or energetic efficiency. Endothermy is associated with higher standard metabolic rates, which may result from high aerobic capacities required by these high‐performance fishes to conduct many aerobic activities simultaneously. A high standard metabolic rate indicates that the benefits of endothermy may be offset by significant energetic costs.

endothermy
water temperature
convergent evolution
mackerel


Enamel microstructure and mastication in Pyrotherium romeroi (Pyrotheria, Mammalia)

Abstract: The South American ungulate Pyrotherium romeroi provides a new enamel type, ''Pyrotheriumenamel''. It is characterized by vertically oriented bands that differ from vertical Hunter-Schreger-bands in being wider and having a specific internal feather-like structure. The enamel is formed exclusively by prisms with keyholeshaped cross sections. This prism type occurs in Proboscidea, Taeniodonta and some Primates and thus evolved independently several times. A slight differentiation between trailing and leading edges was found in the schmelzmuster. In addition to scanning electron microscope examination, the ''reflecting light method'' was applied, especially for the investigation of more extensive structures in the enamel microstructure. The mastication of Pyrotherium is dominated by phase I, which is directed mesially and steeply inclined. An insignificant lingually directed phase II without inclination was deduced from striations. The transverse lophs are very resistant to wear and retain their shear-cutting function for most of the lifetime. Whereas mastication in Pyrotherium is functionally comparable to that of other mammals with bilophodont dentitions, the enamel microstructure provides evidence for new unique morphological specializations in Pyrotheria and does not support connection to any other mammalian order so far discussed.

mastication
pyrotherium romeroi
enamel microstructure


Abstract: Sun, H., Babcock, L.E., Peng, J. & Kastigar, J.M., July 2016. Systematics and palaeobiology of some Cambrian hyoliths from Guizhou, China, and Nevada, USA. Alcheringa 41, xxx–xxx. ISSN 0311-5518. Hyoliths constitute one of the most important groups of early biomineralized metazoans. Abundant hyolith specimens, comprising both hyolithides and orthothecides, from the Balang Formation (Cambrian Stage 4), Guizhou, China, and the Poleta Formation (Cambrian Stages 3–4), Pioche Formation (Stages 4–5) and Emigrant Formation (Stages 4–5) Nevada, USA, add to the early Palaeozoic record of hyoliths from South China and Laurentia, and provide new taxonomic, taphonomic and palaeoecologic information about this group. Hyoliths from the Balang Formation include the hyolithides ‘Ambrolinevitus’ maximus Jiang, 1982, Galicornus seeneus? Val’kov, 1975, Haplophrentis reesei Babcock & Robison, 1988, ‘Linevitus’ guizhouensis sp. nov., Meitanovitus guanyindongensis Qian, 1978, undetermined forms, and undetermined orthothecides. Hyoliths from Nevada include the hyolithides Haplophrentis carinatus (Matthew, 1899), Nevadotheca whitei (Resser, 1938), an undetermined form, and undetermined orthothecides. In the Balang Formation, eocrinoids have been found attached to hyolithide conchs, which supports the view that hyolithides were benthic animals. Haijing Sun* [hjsun1987@163.com], Resources and Environmental Engineering College, Guizhou University, Guiyang 550025, PR China; Loren E. Babcock† corresponding author [babcockloren@gmail.com], School of Earth Sciences, The Ohio State University, Columbus, OH 43210, USA; Jin Peng corresponding author [gzpengjin@126.com], Resources and Environmental Engineering College, Guizhou University, Guiyang 550025, PR China; Jessica M. Kastigar [kastigar.2@osu.edu], School of Earth Sciences, The Ohio State University, Columbus, OH 43210, USA. *Also affiliated with Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, PR China. †Also affiliated with Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden.


Seafood through time: changes in biomass, energetics, and productivity in the marine ecosystem

Abstract: The biomass of marine consumers increased during the Phanerozoic. This is indicated by the increase in both fleshiness and average size of individuals of dominant organisms, coupled with the conservative estimate that dominant organisms in the Cenozoic are at least as abundant as those in the Paleozoic. As faunal dominants replaced one another during the Phanerozoic the general level of metabolic activity increased due to both increase in basal metabolism and increase in more energetic modes of life. This demonstrates that the expenditure of energy by marine consumers has increased with time as well. There is a time lag in the expansion of more energetic life habits from environmental settings known to have high food supply into regions expected to have lower rates of food supply (e.g., bivalves into offshore carbonate environments or deep burrowing deposit feeders into the full range of shelf environments), and a time lag in diversification of energetic modes of life (e.g., predation or deep burrowing deposit feeding) for long intervals after they first appeared. This suggests that the supply of food increased across the whole spectrum of marine habitats during the Phanerozoic. The great diversification of specialized predators especially suggests that biomass increase took place all the way down the food chain to the level of primary production. The development of plant life on land and the impact of land vegetation on stimulating productivity in coastal marine settings, coupled with the transfer of organic material and nutrients from coastal regions to the open ocean, and the increase through time in diversity and abundance of oceanic phytoplankton all point to increased productivity in the oceans through the Phanerozoic.


Research history, taphonomy, and age structure of a mass accumulation of the ornithopod dinosaur Dysalotosaurus lettowvorbecki from the Upper Jurassic of Tanzania

Abstract: The region around Tendaguru Hill in southeastern Tanzania has provided a rich, Late Jurassic dinosaur fauna. Among them, thousands of bones of the basal iguanodontian ornithopod Dysalotosaurus lettowvorbecki have been excavated in the Ig/WJ-quarry northwest of the Tendaguru Hill. The incomplete record of the taphonomic information from the excavation is the main reason for the still inconclusive interpretation of the assemblage as either catastrophic or attritional in origin. In this study, all available historical notes, sketches and field catalogues were analysed and combined with data from CT scans, new taphonomic observations and from bone histological as well as demographic analyses. According to these combined results, the mass accumulation of remains of D. lettowvorbecki consists of four closely associated bonebeds in at least three different stratigraphic levels. The bonebeds are classified as mixed, multitaxic, and monodominant. There is no evidence of abrasion and preburial weathering on the bones suggesting minimal transport distances and duration as well as short preburial exposure times. Although the size/age distributions are bimodally U-shaped, the bonebeds are interpreted as catastrophic in origin due to the restricted spatial extent and the overall uniform preservation of the bones. It is proposed that different herds of D. lettowvorbecki crossed a tidal channel several times during seasonal migration and that each time several to dozens of individuals died. The bodies decomposed and were buried at a barrier or a bend nearby. The demographic conditions as well as the modes of death and burial of D. lettowvorbecki are very similar to the observations made from the modern blue wildebeest in the Masai-Mara Reserve in Kenya. Dysalotosaurus lettowvorbecki , history, demography, taphonomy, Jurassic, Tendaguru, Africa.

taphonomy
mass accumulation
dysalotosaurus lettowvorbecki
tanzania
stratigraphic level


Character evolution and the origin of Caimaninae (Crocodylia) in the New World Tropics: new evidence from the Miocene of Panama and Venezuela

Abstract:
Abstract
 Alligators and caimans share a close relationship, supported by both molecular and morphological characters. The divergence between alligators and caimans has been difficult to discern in the fossil record. Two basal taxa have recently been described from the Miocene of Panama and Venezuela but have not yet been presented in a joint phylogeny. Continued preparation of the type material of the Venezuelan Globidentosuchus brachyrostris Scheyer et al., 2013 has revealed new characters for scoring in a cladistic framework. In addition, the first lower jaw of the Panamanian Centenariosuchus gilmorei Hastings et al., 2013 is described herein, and additional characters were scored. In total, we conducted five cladistic analyses to better understand the character evolution involved in the establishment of Caimaninae. In each case, Globidentosuchus appears as the basal-most of the caimanine lineage, followed by Culebrasuchus mesoamericanus Hastings et al., 2013 from Panama. Stepwise character additions of synapomorphies define progressively more derived caimanines, but stratigraphic context creates ghost lineages extending from the Miocene to Paleocene. The persistence of two basal taxa into the Miocene of northern South America and Central America supports the concept of a relict basal population in this region. This further supports biogeographic hypotheses of dispersals in both directions between North and South America prior to full land connection.


BAYSPLINE: A New Calibration for the Alkenone Paleothermometer

Abstract: The alkenone‐based U 37K′ proxy is a cornerstone of paleoclimatology, providing insight into the temperature history of the Earth's surface ocean. Although the relationship between U 37K′ and sea surface temperatures (SSTs) is robust and well supported by experimental data, there remain outstanding issues regarding the seasonality of production of alkenones and the response of U 37K′ at very warm and cold SSTs. Using a data set of over 1,300 core‐top U 37K′ measurements, we find compelling evidence of seasonal production in the North Atlantic, North Pacific, and Mediterranean Oceans. We also find significant attenuation of the U 37K′ response to SST at warm temperatures (>24°C), with the slope reduced by nearly 50% as U 37K′ approaches unity. To account for these observations in a calibration, we develop a new Bayesian B‐spline regression model, BAYSPLINE, for the U 37K′ paleothermometer. BAYSPLINE produces similar estimates as previous calibrations below ∼24°, but above this point it predicts larger SST changes, in accordance with the attenuation of the U 37K′ response. Example applications of BAYSPLINE demonstrate that its treatment of seasonality and slope attenuation improves paleoclimatic interpretations, with important consequences for the inference of SSTs in the tropical oceans. BAYSPLINE facilitates a probabilistic approach to paleoclimate, building upon growing efforts to develop more formalized statistical frameworks for paleoceanographic reconstruction.

calibration
sst
warm temperature
bayspline


More than One Way of Being a Moa: Differences in Leg Bone Robustness Map Divergent Evolutionary Trajectories in Dinornithidae and Emeidae (Dinornithiformes)

Abstract: The extinct moa of New Zealand included three families (Megalapterygidae; Dinornithidae; Emeidae) of flightless palaeognath bird, ranging in mass from <15 kg to >200 kg. They are perceived to have evolved extremely robust leg bones, yet current estimates of body mass have very wide confidence intervals. Without reliable estimators of mass, the extent to which dinornithid and emeid hindlimbs were more robust than modern species remains unclear. Using the convex hull volumetric-based method on CT-scanned skeletons, we estimate the mass of a female Dinornis robustus (Dinornithidae) at 196 kg (range 155–245 kg) and of a female Pachyornis australis (Emeidae) as 50 kg (range 33–68 kg). Finite element analysis of CT-scanned femora and tibiotarsi of two moa and six species of modern palaeognath showed that P. australis experienced the lowest values for stress under all loading conditions, confirming it to be highly robust. In contrast, stress values in the femur of D. robustus were similar to those of modern flightless birds, whereas the tibiotarsus experienced the highest level of stress of any palaeognath. We consider that these two families of Dinornithiformes diverged in their biomechanical responses to selection for robustness and mobility, and exaggerated hindlimb strength was not the only successful evolutionary pathway.


Deglaciation of the Pacific coastal corridor directly preceded the human colonization of the Americas

Abstract: Dating of rock surfaces and cave bones suggests the North Pacific coast was a viable path for human migration to the Americas. The route and timing of early human migration to the Americas have been a contentious topic for decades. Recent paleogenetic analyses suggest that the initial colonization from Beringia took place as early as 16 thousand years (ka) ago via a deglaciated corridor along the North Pacific coast. However, the feasibility of such a migration depends on the extent of the western Cordilleran Ice Sheet (CIS) and the available resources along the hypothesized coastal route during this timeframe. We date the culmination of maximum CIS conditions in southeastern Alaska, a potential bottleneck region for human migration, to ~20 to 17 ka ago with cosmogenic 10Be exposure dating and 14C dating of bones from an ice-overrun cave. We also show that productive marine and terrestrial ecosystems were established almost immediately following deglaciation. We conclude that CIS retreat ensured that an open and ecologically viable pathway through southeastern Alaska was available after 17 ka ago, which may have been traversed by early humans as they colonized the Americas.

corridor
colonization
early human
cordilleran ice sheet
deglaciation


Mycobacterium tuberculosis complex DNA from an extinct bison dated 17,000 years before the present.

Abstract: In order to assess the presence of tuberculosis in Pleistocene bison and the origin of tuberculosis in North America, 2 separate DNA extractions were performed by 2 separate laboratories on samples from the metacarpal of an extinct long-horned bison that was radiocarbon dated at 17,870+/-230 years before present and that had pathological changes suggestive of tuberculosis. Polymerase chain reaction amplification isolated fragments of tuberculosis DNA, which were sequenced, and on which spoligotyping was also performed to help determine its relationship to the various members of the Mycobacterium tuberculosis complex. Extensive precautions against contamination with modern M. tuberculosis complex DNA were employed, including analysis of paleontologic and modern specimens in 2 geographically separate laboratories.

complex dna
bison
mycobacterium tuberculosis


The transition to foraging for dense and predictable resources and its impact on the evolution of modern humans

Abstract: Scientists have identified a series of milestones in the evolution of the human food quest that are anticipated to have had far-reaching impacts on biological, behavioural and cultural evolution: the inclusion of substantial portions of meat, the broad spectrum revolution and the transition to food production. The foraging shift to dense and predictable resources is another key milestone that had consequential impacts on the later part of human evolution. The theory of economic defendability predicts that this shift had an important consequence—elevated levels of intergroup territoriality and conflict. In this paper, this theory is integrated with a well-established general theory of hunter–gatherer adaptations and is used to make predictions for the sequence of appearance of several evolved traits of modern humans. The distribution of dense and predictable resources in Africa is reviewed and found to occur only in aquatic contexts (coasts, rivers and lakes). The palaeoanthropological empirical record contains recurrent evidence for a shift to the exploitation of dense and predictable resources by 110 000 years ago, and the first known occurrence is in a marine coastal context in South Africa. Some theory predicts that this elevated conflict would have provided the conditions for selection for the hyperprosocial behaviours unique to modern humans. This article is part of the themed issue ‘Major transitions in human evolution’.

resource
modern human
africa
coast
south africa


Dental Ontogeny in Pliocene and Early Pleistocene Hominins

Abstract: Until recently, our understanding of the evolution of human growth and development derived from studies of fossil juveniles that employed extant populations for both age determination and comparison. This circular approach has led to considerable debate about the human-like and ape-like affinities of fossil hominins. Teeth are invaluable for understanding maturation as age at death can be directly assessed from dental microstructure, and dental development has been shown to correlate with life history across primates broadly. We employ non-destructive synchrotron imaging to characterize incremental development, molar emergence, and age at death in more than 20 Australopithecus anamensis, Australopithecus africanus, Paranthropus robustus and South African early Homo juveniles. Long-period line periodicities range from at least 6–12 days (possibly 5–13 days), and do not support the hypothesis that australopiths have lower mean values than extant or fossil Homo. Crown formation times of australopith and early Homo postcanine teeth fall below or at the low end of extant human values; Paranthropus robustus dentitions have the shortest formation times. Pliocene and early Pleistocene hominins show remarkable variation, and previous reports of age at death that employ a narrow range of estimated long-period line periodicities, cuspal enamel thicknesses, or initiation ages are likely to be in error. New chronological ages for SK 62 and StW 151 are several months younger than previous histological estimates, while Sts 24 is more than one year older. Extant human standards overestimate age at death in hominins predating Homo sapiens, and should not be applied to other fossil taxa. We urge caution when inferring life history as aspects of dental development in Pliocene and early Pleistocene fossils are distinct from modern humans and African apes, and recent work has challenged the predictive power of primate-wide associations between hominoid first molar emergence and certain life history variables.


Trunk regionalization and functional morphology of the globally distributed trilobite Bathynotus from Cambrian Series 2 of China

Abstract: This study presents a case in trunk regionalization and functional morphology of redlichiid trilobites, based on a globally distributed Bathynotus, collected from the base of the Kaili Formation in the late Cambrian Series 2 of China. This micropygous trilobite processed a body pattern with four types of thoracic tergites within two batches at maturity: a homonymous morphotype with similar thoracic tergite structure throughout the anterior portion of the thorax, and a heteronomous morphotype in the posterior portion of the thorax, with a pair of macropleurae in the 11th thoracic tergite and two pairs of tiny pleurae (micropleurae) in the 12th and 13th thoracic tergites. The unique morphology by regionalization in Bathynotusis considered closely related to its articulation structures and the ability to perform encapsulated enrolment, permitting the posterior trunk tergites with long pleural spines to fully cover the ventral cephalic shield during dorsal flexure. The regional integration of trunk tergites into structural regions provides the opportunity to trace the origin of their functional morphology and behavior in the evolutionary process of trilobite caudalization.

functional morphology
cambrian series
trunk regionalization


Collective behaviour in 480-million-year-old trilobite arthropods from Morocco

Abstract: Interactions and coordination between conspecific individuals have produced a remarkable variety of collective behaviours. This co-operation occurs in vertebrate and invertebrate animals and is well expressed in the group flight of birds, fish shoals and highly organized activities of social insects. How individuals interact and why they co-operate to constitute group-level patterns has been extensively studied in extant animals through a variety mechanistic, functional and theoretical approaches. Although collective and social behaviour evolved through natural selection over millions of years, its origin and early history has remained largely unknown. In-situ monospecific linear clusters of trilobite arthropods from the lower Ordovician (ca 480 Ma) of Morocco are interpreted here as resulting either from a collective behaviour triggered by hydrodynamic cues in which mechanical stimulation detected by motion and touch sensors may have played a major role, or from a possible seasonal reproduction behaviour leading to the migration of sexually mature conspecifics to spawning grounds, possibly driven by chemical attraction (e.g. pheromones). This study confirms that collective behaviour has a very ancient origin and probably developed throughout the Cambrian-Ordovician interval, at the same time as the first animal radiation events.


Prey Selection by naticid gastropods: experimental tests and application to the fossil record

Abstract: Because predation by drilling gastropods is uniquely preservable in the fossil record, it represents important evidence for the study of coevolution. Previous studies of drilling gastropod predation have been largely descriptive and sometimes contradictory. We formulate and test a model of prey selection by naticid drilling gastropods. The model adequately predicts both prey species selection and prey size selection. Prey preferences parallel prey profitabilities, determined by calculating prey species-specific and predator size-specific cost-benefit functions. The model also specifically suggests the evolution of potential refugia from predation and the evolution of potential predatory attributes. Application of the model to several Miocene and Pliocene assemblages studied by Thomas (1976) corroborates the feasibility and utility of this approach in examining the evolutionary record of naticid predation, which extends from the Late Mesozoic. Apparent evolutionary stasis and convergent morphological trends among prey species may be consistent with continuous selection pressures against predation.

naticid gastropod
application
prey selection


Mollistephaninae and Frebolditinae, new subfamilies of Middle Jurassic stephanoceratid Ammonoidea

Abstract:
Two new Bajocian stephanoceratid subfamilies are distinguished based on morpho-structural criteria and phyletic patterns. At the Aalenian/Bajocian transition, Stephanoceratinae of the genus Albarracinites are the source of the earliest species of Mollistephanus and of the new Mollistephaninae lineage that includes three successive genera: Mollistephanus, Paramollistephanus gen. nov. and Phaulostephanus. The Mollistephaninae span across the Mediterranean-Caucasian Subrealm during the lower Bajocian, but Paramollistephanus is pandemic to both the Mediterranean-Caucasian and East Pacific subrealms during the Propinquans Zone. The Frebolditinae evolved from Paramollistephanus in the lower Bajocian, beginning with Freboldites and giving rise to diverse genera such as Parabigotites, Patrulia, Bajocia, Subcollina and Parastrenoceras that occur into the upper Bajocian of both the East Pacific and Mediterranean-Caucasian subrealms.
Palaeobiogeographical and phylogenetic data of these two subfamilies support an active Bajocian Central-Atlantic Seaway, the so-called Hispanic Corridor, as a bidirectional, biodispersal route driven by changes of the relative sea level. Several bioevents of appearance, immigration and dispersal, associated with the range expansion of ammonoid taxa, were effective (Paramollistephanus in the latest Laeviuscula Zone, Subcollina in the latest Humphriesianum Zone, and Parastrenoceras in the earliest Niortense Zone). Based on life-history strategy, morphostructural and functional criteria, the dimorphic Caumontisphinctes-Infraparkinsonia pair seems to be the origin of the Parkinsoniidae. The Mollistephaninae and Frebolditinae show small adult size, scarcity of fossils, and low stratigraphic persistence and constancy; however, they present some pandemic genera of the Tethys-Panthalassa Realm and display high resolution for time correlation between the western Tethyan and eastern Pacific marine basins of separate bioprovinces.


Intraspecific variation of phragmocone chamber volumes throughout ontogeny in the modern nautilid Nautilus and the Jurassic ammonite Normannites

Abstract: Nautilus remains of great interest to palaeontologists after a long history of actualistic comparisons and speculations on aspects of the palaeoecology of fossil cephalopods, which are otherwise impossible to assess. Although a large amount of work has been dedicated to Nautilus ecology, conch geometry and volumes of shell parts and chambers have been studied less frequently. In addition, although the focus on volumetric analyses for ammonites has been increasing recently with the development of computed tomographic technology, the intraspecific variation of volumetric parameters has never been examined. To investigate the intraspecific variation of the phragmocone chamber volumes throughout ontogeny, 30 specimens of Recent Nautilus pompilius and two Middle Jurassic ammonites (Normannites mitis) were reconstructed using computed tomography and grinding tomography, respectively. Both of the ontogenetic growth trajectories from the two Normannites demonstrate logistic increase. However, a considerable difference in Normannites has been observed between their entire phragmocone volumes (cumulative chamber volumes), in spite of their similar morphology and size. Ontogenetic growth trajectories from Nautilus also show a high variation. Sexual dimorphism appears to contribute significantly to this variation. Finally, covariation between chamber widths and volumes was examined. The results illustrate the strategic difference in chamber construction between Nautilus and Normannites. The former genus persists to construct a certain conch shape, whereas the conch of the latter genus can change its shape flexibly under some constraints.

phragmocone chamber volume
nautilus
intraspecific variation


Overview of Mesozoic crocodylomorphs from the Junggar Basin, Xinjiang, Northwest China, and description of isolated crocodyliform teeth from the Late Jurassic Liuhuanggou locality

Abstract: Lacustrine and fluvial Jurassic and Cretaceous sediments in the Junggar Basin yielded at least five crocodylomorph taxa. The Middle and Late Jurassic Shishugou Formation has produced the crocodylomorph Junggarsuchus sloani, the holotype specimen of the middle-sized, amphibious goniopholidid Sunosuchus junggarensis, and remains of the shartegosuchid crocodyliform Nominosuchus matutinus. The contemporary Qigu Formation has also yielded Sunosuchus. Two crocodyliforms have been reported based on cranial and postcranial material from the Early Cretaceous Tugulu Group. The cranial material has been assigned to Edentosuchus tienshanensis, representing the geologically youngest protosuchid. In recent years, screenwashing at the Liuhuanggou locality, 40 km southwest of the city of Urumqi, has yielded a large number of isolated crocodyliform teeth in a highly fossiliferous bonebed within the Late Jurassic Qigu Formation. At least three different tooth morphologies can be distinguished at Liuhuanggou, indicating a shartegosuchid, juveniles cf. Sunosuchus and an unidentified mesoeucrocodylian. Thus, the variety in crocodyliforms known from this region is increased. The faunal composition comprises a mix of basal and derived crocodyliforms similar to that of the upper part of the Shishugou Formation and differs from contemporary European and many North American deposits. Hence, crocodyliform diversity in the Junggar Basin comprises at least two different size classes in the Junggar ecosystem: whereas the most frequently found taxon, Sunosuchus, was a larger (3 m) amphibious mesoeucrocodylian, the other taxa were smaller (<1.5 m long) and possibly more terrestrial faunal components. The combination of phylogenetically different crocodylomorphs and different ecotypes may reflect climate changes and hints towards the presence of relict faunas.

crocodylomorph
junggar basin
crocodyliform tooth


The cave bear’s hibernation: reconstructing the physiology and behaviour of an extinct animal

Abstract: Abstract When studying an extinct species such as the cave bear (Ursus spelaeus ROSENMÜLLER 1794), it is possible to apply a variety of molecular biology techniques such as the study of stable isotopes or mitochondrial DNA (mDNA) to infer patterns of behaviour or physiology that would otherwise remain concealed. Throughout Europe and along time, differences in the isotopic values (δ13C and δ15N) of cave bears arise from environmental differences and the Pleistocene climatic evolution. The climate determines the hibernation length, during which the cave bears undergo a particular physiology that can be related to an increase in δ15N during climate cooling. In order to verify whether hibernation affected the isotopic values, we compared cave bears in different ontogenetic stages. The results show that perinatal values reflect the values for mothers during hibernation, while juveniles show differences in maternal investment. A previous study in the literature based on complete mitochondrial DNA sequences of several individuals collected from closely situated caves showed that each cave housed, almost exclusively, a single lineage of haplotypes. This pattern suggests extreme fidelity to the birth site, or homing behaviour, and that cave bears formed stable maternal social groups, at least for the purpose of hibernation. Studies of this type offer unexpected data on the palaeobiology of this extinct animal.