BPT25-01

Room:202

Time:May 24 14:15-14:30

Stem and crown evolution: United grand theory of life evolution
MARUYAMA, Shigenori1∗ ; EBISUZAKI, Toshikazu2
1

Earth-Life Science Institute, Tokyo Institute of Technology, 2 RIKEN

Evolutional theories have long been discussed since 19th century. One of the most famous theory of evolution was proposed byDarwin about 150 years ago. Since then, Gould’s punctuated equilibrium theory, Kimura’s neutral evolution etc were proposed
and recently molecular biology is rapidly developing. However, there is discrepancies in proposed phylogenic trees due totheoretical differences to analyze. So, we tried to implicate the evolution of history from synthetic paleogeographic map basedon geological evidences including fossil data.
As a result, we propose there are two significant patterns of evolution through Earth history. One is stem evolution which occur
at continental rift where atomic bomb magma erupt to accelerate the birth of new species by mutation. The other pattern is crownevolution that progress when continents collide after species were evolved in isolated environment such as places on fragmented
continents. At the same time of those patterns of evolution, fluctuation happened in the Universe five huge impact on life history
which is mass extinction. Activities such as starburst and collision between solar system and a dark nebula was the trigger tocause mass extinction and subsequent rebirth of another ecosystem on the Earth.

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BPT25-02

Room:202

Time:May 24 14:30-14:45

What is main marine primary producer during the Cretaceous OAEs?: Evidences frommarine kerogens.
ANDO, Takuto1∗ ; SAWADA, Ken1 ; TAKASHIMA, Reishi2 ; NISHI, Hiroshi2
1

Faculty of Science, Hokkaido University, 2 Tohoku University Museum, Tohoku University

The mid-Cretaceous oceanic anoxic events (OAEs) are important to understand extremely greenhouse world. It is thought thatenhanced marine productivity caused the global anoxia, although coccolithophorid and dinoflagellate productivity were diminished during the OAEs. Distinct algal biomarkers such as 2-methyl hopanoid and isorenieratane in the OAE levels indicate highactivities of cyanobacteria and green sulfur bacteria, although detection of these biomarkers was limited. Amorphous organic
matter (AOM) and very small palynomorph such as acritarchs are main components of OM in black shale but they were removed
at the time of palynomorph analysis with size fractionation. In the present study, we analyzed kerogen including AOM and small
acritarchs by fluorescent microscope and pyrolysis/thermochemolysis method to reconstruct variation in primary producers during OAEs.
Black shales were collected from the Goguel (OAE1a), Jacob, Kilian, Paquier (OAE1b), Breistroffer (OAE1d) and Thomel(OAE2) levels in SE France. These crushed samples were extracted with ultrasonication and their residues were sequentiallytreated by acids in a water bath shaker (Sawada et al., 2012). AOM classified into NFA (non-fluorescent AOM; wood origin), WFA (weakly fluorescent AOM; marine plankton origin) and FA (fluorescent AOM; cuticle or palynomorph origin), andacritarchs divided into five groups (sphaeromorph, pteromorph, acanthomorph, netromorph, polygonomorph). We analyzed pyrolysis and thermochemolysis of kerogen by using GC-MS equipped a Curie-point pyrolyzer.
Kerogens in the Goguel (OAE1a) samples are mainly comprised of WFA, and percentages of WFA (WFA%) are slightly
higher in black shale samples. Green algal phycoma-like acritarchs, sphaeromorph, are abundant in the Goguel level, especiallyacme phase of OAE1a. Anoxia during the OAE1a might be related to high production of green algae. Terrestrial NFA are main
components in all OAE1b samples, although WFA are higher in black shale samples of the Kilian and Paquier levels. These
data show both enhanced marine production and excess terrestrial input led anoxia during the OAE1b. Sphaeromorph are also
observed from black shales samples of OAE1b level s. In addition, percentages of long-spine type acanthomorph are higher
in the Paquier level. The WFA% values are remarkably higher in the OAE1d and 2 samples, especially black shales of OAE2
(80-90%), which suggest that enhanced productivity during the OAE1d and OAE2. Netromorph, which has each spine in bipolar,
is observed in only OAE1d samples. Sphaeromorph decrease but acanthomorph increase with decreasing WFA% values in the
Trough interval (cooling phase) of the OAE2 level. 2-methyl hopane and a large amount of branched alkanes are detected bypyrolysis/thermochemolysis analysis from the OAE1a and OAE1b samples, respectively. These pyrolysis results are consistent
with those of free biomarkers. Branched alkanes were characteristically detected as pyrolysate of WFA in accumulated layersof the Paquier level, and the relative abundances of these compounds correlated with free tail-to-tail isoprenoid concentration.
These tail-to-tail isoprenoids are presumably derived from lycopanoid skeleton of marine phytoplankton such as green algae,
which is supported by the results of kerogen.
Keywords: Oceanic Anoxic Events (OAEs), kerogen, acritarch, palynofacies, pyrolysis, thermochemolysis

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BPT25-03

Room:202

Time:May 24 14:45-15:00

Paleotemperature, productivity and shell size of Hedbergella delrioensis in the Cretaceous
thermal maximum
MORIYA, Kazuyoshi1∗ ; TSUTSUI, Keita1
1Dep. Earth Sciences, Sch. Education, Waseda Univ.

Planktic foraminifers, experienced two major diversity crises at the Cretaceous/Paleogene boundary and the Eocene/Oligocene
boundary, have emerged in late Jurassic and repeatedly flourished in these 100 myr Earth history (e.g. Norris, 1991). Amongthem, the Cretaceous foraminifers diversified in the greenhouse interval. Morphologies of some Cretaceous species are very
unique, and never reappeared after the K/Pg boundary (Norris, 1991). Its diversity has widely been discussed in relation withoceanic anoxic events in the mid-Cretaceous (e.g. Leckie et al., 2002).
On the other hand, size distribution within a modern planktic foraminiferal community, and intra-species size variation are
known to respond to abiotic properties, such as temperature and salinity, and productivity (Bijma et al., 1990a, 1990b; Schmidt
et al., 2004). However, the size distribution of the Cretaceous foraminifers has not been widely analyzed so far. We discuss
the intra-species size variation of the mid-Cretaceous planktic foraminifer, Hedbergella delrioensis , and environmental qualities;
paleotemperature, salinity and productivity.
Pelagic sediments used for this study were recovered in ODP Leg 207 at Demerara Rise, the equatorial Atlantic. Samples were
washed through a sieve with 64µm opening. Approximately 100 individuals of H. delrioensis were picked from particles larger
than 125 µm. The largest linear dimension of each individual was measured, and the stratigraphic variation of average size wasdescribed. Since TEX86 and carbon and oxygen isotope composition of planktic foraminifers have already been analyzed by
Forster et al. (2007) and Moriya et al., (2007), stratigraphic variations of these proxies were discussed with the size distribution.
Average size of H. delrioensis co-varies with the productivity estimated from the carbon isotope composition. Considering thatthe paleotemperature and salinity had been unchanged in the interval analyzed, it is expected that the size of H. delrioensis
responded to the local productivity.
Bijma, J. et al. (1990) Jour Foram Res. 20, 117-127.
Bijma, J. et al. (1990) Jour Foram Res. 20, 95-116.
Forster, A. et al. (2007) Geology. 35, 919-922.
Leckie, R. M., et al. (2002) Paleoceanography. 17, 10.1029/2001PA000623.
Moriya, K. et al. (2007) Geology. 35, 615-618.
Norris, R. D. (1991) Paleobiology. 17, 388-399.
Schmidt, D. N. et al. (2004) Mar Micropaleontol. 50, 319-338.

Keywords: Cretaceous, planktic foraminifer, shell size, paleotemperature, productivity

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BPT25-04

Room:202

Time:May 24 15:00-15:15

Durophagous predation on scaphitid ammonoids in the Late Cretaceous Western Interior
Seaway of North America
TAKEDA, Yusuke1∗ ; TANABE, Kazushige2 ; SASAKI, Takenori2 ; LANDMAN, Neil H.3
1

Department Earth and Planetary Science, The University of Tokyo, 2 The University Museum, the University of Tokyo, 3 American
Museum of Natural History
The study of the evolution of predator-prey interactions has contributed much to our understanding of the ecological background of biodiversity change through geological time, because they represent a driving force of natural selection. This study isthe first to report a trend of predation intensity on scaphitid ammonoids from the Turonian to the Maastrichtian (Late Cretaceous)on the basis of analysis of ventral shell breakage in large samples from the U.S. Western Interior Province. Analysis of 835
adult specimens revealed ventral shell breakage in 50 specimens. In most of the damaged specimens, the breakage occurred in apreferred position at the rear part of the body chamber. Ventral breakage is rare in the Turonian specimens, whereas it is common
in the Campanian and Maastrichtian specimens. The shell diameter of adult scaphitid ammonoids tends to increase with time.
The position of the breakage and the absence of repairs indicate that the ventral breakage resulted from lethal predation. Basedon the incidence of breakage and the size and shape of the breaks, possible predators include fish, reptiles, and cephalopods suchas Placenticeras , Eutrephoceras , and coleoids. Our statistical analysis of ventral shell breakage indicates that the incidence of
lethal predation increased in conjunction with an increase in adult shell size, suggesting that the body size of the prey was animportant factor in predator?prey interactions. In addition, the predatory damage is more extensive in larger adults.

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BPT25-05

Room:202

Time:May 24 15:15-15:30

Origin and rapid dispersal of oceanic dolphins (Odontoceti: Cetartiodactyla) based on theoldest fossil record.
HIRAMOTO, Jun1∗ ; KOHNO, Naoki2
1

University of Tsukuba, 2 National Museum of Nature and Science and University of Tsukuba, Japan

Oceanic dolphins (Delphinidae), such as killer whales, pilot whales and bottlenose dolphins, comprise approximately 36 extant species in 17 ˜19 genera, which makes them the most speciose group of cetaceans inhabiting the modern ocean. Despite
their current diversity, the fossil record of delphinids is very limited, and it remains unclear how and when they first originated.
Molecular clock analyses date the divergence of delphinids from other delphinoids (porpoises, belugas and narwhals) to the
Early or Middle Miocene (about 23 ˜14 Ma). By contrast, the so far ”oldest” extinct taxon confidently referred to the group Eodelphinus kabatensis from Hokkaido - is no older than Late Miocene (about 9 Ma). Thus, there is a considerable gap between
the estimated time of origin as inferred from molecular data and the fossil record, respectively.
Here, we re-examine the extinct dolphin Sinanodelphis izumidaensis Makiyama, 1936, which is known from a relatively wellpreserved skull and associated partial skeleton from the Middle Miocene Bessho Formation (approximately 13. 6˜11. 8 Ma),
Nagano Prefecture, central Japan. Although initially described as a delphinid, later studies classified this species as Delphinoidea
incertae sedis because of a lack of diagnostic characters and the incomplete preparation and limited accessibility of the holotype(the latter has been designated as a Natural Monument of Nagano Prefecture). For our analysis, we studied both the holotype(via direct observation and CT scanning) and two undescribed specimens (previously reported as Delphinoidea fam., gen. et sp.
indet.) that were recovered from nearly the same locality and horizon. All of the specimens are similar in terms of general skull
proportions, in having numerous, small teeth, and in having markedly asymmetrical external bony nares, indicating that they
likely belong to the same species.
We performed phylogenetic analysis based on 84 species (all odontocetes) and 278 morphological characters, with the archaeocetes Georgiacetus and Zygorhiza used as out-group. Our results identify S. izumidaensis as one of the earliest diverging
members of crown Delphinidae. This placement extends the fossil record of delphinids to ca. 14 ˜12 Ma, only slightly younger
than - and therefore in agreement with - the youngest molecular divergence dates. A further, as yet undescribed fossil delphinid
apparently also occurs in the Middle or Late Miocene (13. 6 ˜10. 3 Ma) of California. Together, S. izumidaensis and the Californian material demonstrate that delphinids may have inhabited both sides of the North Pacific as little as 1 Ma after their presumed
time of origin. This, in turn, may be indicated that dolphins underwent a phase of rapid geographical dispersal early during theirevolutionary history.

Keywords: Sinanodelphis izumidaensis, Delphinidae, Middle Miocene, Bessho and Aoki Formation

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BPT25-06

Room:202

Time:May 24 15:30-15:45

Benthic-pelagic coupling in Pliocene ocean: Geochemical and micropaleontologic evidence in the ichnofossil Phymatoderma
IZUMI, Kentaro1∗
1

Center for Environmental Biology and Ecosystem Studies, NIES

Numerous studies have revealed the evidence of benthic-pelagic coupling in various ocean areas. In terms of marine benthos,
it is well known that feeding, growth and reproduction are generally synchronized with the seasonal input of phytodetritus to thesea-floor. However, compared to examples of modern organisms, little is known about the evidence of the ancient benthic-pelagic
coupling. Thus, the present study carried out the geochemical and microscopic analyses of the fecal pellet-filled ichnofossil
Phymatoderma from the Pliocene deep-sea strata. The aim of this study is to assess whether benthic-pelagic coupling functioned
in the ancient ocean, with special attention to the temporal relationship between phytodetritus input and deposit feeding by thetrace-maker. Elemental analysis revealed that Ca, which is probably derived from the calcareous microfossils, is significantly
accumulated in the tuffaceous pellets. Because the CaO content of the pelletal infill are generally similar to that of the hostsiltstones, it may be concluded that the recognized Ca accumulation in pellets does not reflect diagenetic alteration. SEM observations showed the presence of various types of microfossils (i.e., coccoliths, diatoms, planktonic foraminifera, radiolaria)
within the pelletal infill of Phymatoderma . In addition, excreted tuffaceous fecal pellets are occasionally found to be composed
exclusively of coccoliths. Considering all these lines of evidence, it is most likely that the deposit-feeding by the Phymatoderma producer was synchronized with an episodic (probably seasonal) coccolithophore bloom deposition on the deep-sea floor. The
reconstructed feeding strategy may have facilitated the effective uptake of freshly deposited phytodetritus. This interpretation isquite reasonable because such a mode of feeding has been commonly recognized in the case of deep-sea deposit-feeding macroand megabenthos. In summary, this study provides geologic evidence for benthic-pelagic coupling in the Pliocene ocean.

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BPT25-P01

Room:Convention Hall

Time:May 24 18:15-19:30

A remain of a gigantic oviraptorosaurian (Dinosauria: Theropoda) from the Upper Cretaceous of the Gobi Desert
TSUIHIJI, Takanobu1∗ ; WATABE, Mahito2 ; BARSBOLD, Rinchen3 ; TSOGTBAATAR, Khishigjav3
1

The University of Tokyo, 2 Osaka City University, 3 Mongolian Paleontological Center

A large, isolated symphyseal region of fused contralateral dentaries belonging to a caenagnathid oviraptorosaurian was foundin the lower Upper Cretaceous Bays Shire Formation cropping out at Tsagaan Teg in the Mongolian Gobi Desert. This specimen is comparable in size and morphology to the gigantic caenagnathid Gigantoraptor erlianensis known from the Iren Dabasu
Formation in China, and may be closely related to the latter species. The occurrence of the specimen of a possible affinity
with G. erlianensis in the Bays Shire Formation is consistent with the hypothesized correlation between the Bayn Shire and Iren
Dabasu formations proposed based on vertebrate fossils, especially turtles.
Keywords: Mongolia, Gobi Desert, Oviraptorosauria, Cretaceous, Dinosauria

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BPT25-P02

Room:Convention Hall

Time:May 24 18:15-19:30

Desmostylian phylogenetic relationship revisited
MATSUI, Kumiko1∗
1

Department of Earth and Planetary Science, University of Tokyo

Desmostylia is an extinct clade of marine mammals. They belong to Tethytheria or possibly Perissodactyla. They lived in
North Pacific Rim from earliest Oligocene to earliest Late Miocene and are already extinct at the order level. Traditionally,
Desmostylia has been divided into two families, Desmostylidae and Paleoparadoxiidae, based on their teeth morphology, withthe former including 4 or 5 genera (Ashoroa , Cornwallius , Kronotherium , ”Vanderhoofius” , and Desmostylus ) and the latter4 genera (Behemotops , Archaeoparadoxia , Paleoparadoxia , Neoparadoxia ). Although the phylogenetic relationships within
Desmostylia have been mostly unclear, two hypotheses were proposed: either both Desmostylidae and Paleoparadoxiidae aremonophyletic groups, or Paleoparadoxiidae comprise paraphyletic outgroups for Desmostylidae. One factor contributing to suchdifference in the hypothesis was the lack of well-preserved specimens that can be used as suitable outgroups for phylogenetic
analyses. Cooper et al. (2014), however, described a well-preserved skull of Anthracobne that is considered as an appropriate
outgroup of Desmostylia. In this study, at first, I ran analyses on data matrices on the desmostylian interrelationship published inprevious studies to examine reproducibility of the results, i.e., whether or not tree topologies reported in these studies could berecovered. Second, I analyzed the Desmostylian relationship by newly adding Anthracobne as an out-group to such data sets after
examining the accuracy of their character coding. Phylogenetic analysis was conducted with equally weighted parsimony using
TNT v. 1.1 (Goloboff et al. 2008). One thousand replicates of tree bisection reconnection branch swapping were run holding ten
trees per replicate with all zero-lengths branches collapsed. For this analysis, published data sets were combined and revised toinclude 5 species of Desmostylia and 5 species of Paleoparadoxiidae. A whole data matrix including both cranial and postcranial
characters and a culled matrix including cranial characters only were separately analyzed. In this analysis, analyses on both
the whole and culled data sets resulted in Paleoparadoxiidae forming paraphyletic, successive outgroups for the monophyletic
Desmostylidae. This result provides a phylogenetic framework for discussing various aspects of Desmostylian evolution.
Reference
Cooper et al. (2014). Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls. PLoS One
9(10): e109232.
Goloboff et al. (2008). TNT, a free program for phylogenetic analysis. Cladistics 24: 1-13.

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BPT25-P03

Room:Convention Hall

Time:May 24 18:15-19:30

Avian wing loading and aspect ratio correlate with track
TANAKA, Ikuko1∗
1

Graduate School of Science, Kobe University

Avian have two completely different styles of locomotion, flight and bipedal walking, and use them properly dependingon situations. Avian track shapes are divided into three groups corresponding to habitat types, suggesting bipedal walking iscontrolled by habitats. Is flight, another locomotion type, controlled the same? To investigate it, we obtained data of wing shapes
and bodyweights from modern birds, and examined if they showed similar groupings related to habitats. Multiple regression
analyses reveal that wing loadings and wing aspect ratios for birds in each group defined by track shapes exhibit separate clusters
that do not overlap with each other. This result shows that wings are also divided into three groups corresponding to habitat types,
the same with track shapes. Thus, habitats unambiguously affect avian flight as well as walking. Past avian wings are seldom
remained as fossils, whereas past avian tracks are often preserved fossilized. The correspondence relation between wing aspectratio/wing loading and track shapes may constrain the past avian flight ecology and behavior from fossilized track records.
Keywords: ornithology, wing morphology, flight ecology, avian locomotion, multiple regression analysis, paleobiology

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BPT25-P04

Room:Convention Hall

Time:May 24 18:15-19:30

Implication of peculiar internal fracturing in fossil nautiloids
KARASAWA, Tomoki1∗ ; MAEDA, Haruyoshi2
1Graduate school of Science, Kyoto University, 2 The Kyushu University Museum

Extinct Miocene nautiloid Aturia cubaensis from Uchiura Group (Fukui Prefecture) shows internal septa fragmentation though
the outer wall is intact. Similar broken nautiloids fossils with intact outer walls and fragmented septa have been reported since
1980s and were interpreted as ’implosion’, the fragmentation by increasing ambient water pressure during a dead shell sinks.
In these A. cubaensis , however, sipluncles are filled with mud and mangled. This indicates this fragmentation occurred after aburial of the empty shell.
Septal fragmentation occurs at adapically half from a last septum. Intact air chambers are filled with grayish white mudstone
though a fossil matrix is dark gray mudstone. Former is composed of matrix-supported and high porosity (about 25 - 35 %) andlatter is grain-supported and low porosity (below 20 %). On the other hand, porosity of mudstone infilling of the siphuncle has
usually high (more than 40 %). Especially it is highest at the collapse boundary between intact air chambers and fragmented
septa (up to 70 %). In addition, clay minerals concentrates in the siphuncle near the collapse boundary. These lines suggestthat the siphuncle-infilling soaks up the water in air chambers in diagenesis. This depressurizes insides of air chambers and thus
makes considerable pressure difference between inside and outside of a buried nautilus shell, and finally septa collapse.
This internal fragmentation has not been found from ammonoids. Deformation of ammonoids occurs in outer walls mainly andcan be explained by simple compactional process except for dissolution. This suggests difference of strength of structure between
shells of nautiloids and ammonoids. Detailed taphonomic analysis could be a clue to structural mechanics of cephalopods shells.
Keywords: taphonomy, nautiloid, Miocene, diagenesis

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BPT25-P05

Room:Convention Hall

Time:May 24 18:15-19:30

Chemotaxonomic fingerprints of alkenones and alkenoates in sediments of Lake Naga-ike
on the Skarvsnes, Antarctica
NAKAMURA, Hideto1∗ ; TAKEDA, Mayumi1 ; SAWADA, Ken1 ; TAKANO, Yoshinori2
1

Hokkaido Univ., 2 JAMSTECLong chain alkenones and alkenoates are widely distributed in marine sediments and their extent of unsaturation (UK 37 ,U 37 ) is extensively used for reconstruction of paleo sea surface temperature. Alkenones and related compounds have also been
detected in various lakes, although there is a wide variation in alkenone compositions and the temperature calibrations between individual settings. These variations probably reflect the difference in alkenone producing species (strains) in lakes. Indeed, recent
DNA analysis revealed that multiple lineages of the order Isochrysidales are distributed among alkenone containing lakes, andis considered to be engaged in the alkenone production (2-3). Culture based investigation on temperature calibrations suggested
the significant variation of calibrations among Isochrysidaceae species (Isochrysis galbana (4), Pseudoisochrysis paradoxa (5)and Chrysotila lamellosa (6)). Therefore, taxonomic identification of alkenone producers is essential to the proper selection ofcalibrations and thus lead to better application of alkenone paleothermometer in lakes.
To elucidate chemotaxonomic characteristics of the compositions of alkenone and related compounds, we have been cultured 9 strains covering all 3 genera (Chrysotila , Isochrysis , Tisochrysis ) of the family Isochrysidaceae, and proposed that thelack of tetraunsaturated alkenones are common characteristic for genus Tisochrysis (7). In this study, cultured Isochrysidaceae
strains as well as sediments of antarctic lake Naga-ike were examined further into the compositions of alkenones and alkenoates.
We discuss chemotaxonomic feature of triunsaturated alkenone isomers and novel C38 alkenoate which could be identified by arecently-developed method (8) using gas chromatography column with dipole selective stationary phase. Isomer of triunsaturated
alkenones have previously identified from high latitude lakes (BrayaSø, Toolik Lake), which are characterized by a significant
proportion of triunsaturated isomers ranging C37 -C39 (8). Meanwhile, triunsaturated alkenone isomer detected from C. lamellasa
were solely C38 . Occurrence of C38 triunsaturated isomers along with novel C38 alkenoate are proposed as characteristics of
C. lamellosa in the family Isochrysidaceae.
Lake Naga-ike is a freshwater lake on the Skarvsnes, Antarctica, and biomarker analysis has been carried out by (9) revealing
ca. 3000 yrs record of alkenone compositions. Examination of the sediment of Lake Naga-ike by a new method (8) revealed
that the co-occurence of C38 triunsaturated alkenone isomers and novel C38 alienate, suggesting a possible contribution of
C. lamellosa . By using a calibration obtained from a culture strain C. lamellosa calibration (6), paleotemperature are calculated
to be 9.2-15 ℃ in surface sediments of Lake Naga-ike. The estimated temperatures are concordant with a summer temperatureof lake waters observed in Naga-ike, while other known culture based calibrations estimated extremely-low temperatures. This
result may afford collateral evidence for the occurrence of alkenone producer closely related to C. lamellasa .
K01) Prahl, F. G. and Wakeham, S. G., 1987. Nature, 330, 367-369.
2) Theroux, S., et al., 2010. Earth Planet. Sci. Lett. 300, 311-320.
3) Toney, J. M., et al., 2010. Geochim. Cosmochim. Acta 74., 1563-1578.
4) Versteegh, G. J. M., et al., 2000. Org. Geochem. 32, 785-794.
5) Theroux, S., et al., 2013. Org. Geochem. 62, 68-73.
6) Nakamura, H., et al., 2014. Org. Geochem. 66, 90-97.
7) Nakamura, H., et al., 2014. JGS Annual Meeting 2014.
8) Longo, W. M. et al., 2013. Org. Geochem. 65, 94-102.
9) Sawada, K. et al., 2014, AGU Fall Meeting 2014, B21E-0093.
Keywords: alkenone, Haptophytes, chemotaxonomy, lake sediments, paleothermomater

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BPT25-P06

Room:Convention Hall

Time:May 24 18:15-19:30

An index of morphological turnover across a chronological boundary
UBUKATA, Takao1∗
1

Kyoto University

Study on morphological diversity over geologic time has been conventionally based on the patterns of disparity change. Change
in disparity across a mass extinction event is determined by the relationship between a temporary decrease in morphological variation and subsequent introduction of new variation after the event. In the case of a balanced relationship, the disparity remains
constant throughout the interval, even if the morphology was totally changed. An alternative approach is an analysis of morphological turnover in which appearance patterns of morphospace occupation are compared between the adjacent geochronologicalunits. However, conventional morphospace analyses have omitted abundance of each species. Here, I would introduce an index
representing how drastically the pattern of morphospace occupation changes. The index takes into account the abundance of eachspecies based on the collection-based occurrence data deposited in the Paleobiology Database. The analysis of the morphologicalturnover begins with depicting the landscape of the probability density of data in a morphospace for each chronological bin using
multi-dimensional kernel density estimation. The similarity between a pair of the landscapes can be represented by a correlation
coefficient of the probability density computed for each point in the multi-dimensional morphospace. The value of 1 minus
the correlation coefficient is defined as an index of morphological turnover. This index is sensitive to change in morphospace
occupation pattern.
Keywords: morphospace, disparity, mass extinction and recovery

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