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
1Earth-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 fragmentedcontinents. 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 organicmatter (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 smallacritarchs 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. Thesedata show both enhanced marine production and excess terrestrial input led anoxia during the OAE1b. Sphaeromorph are alsoobserved from black shales samples of OAE1b level s. In addition, percentages of long-spine type acanthomorph are higherin 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 theTrough 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 areknown 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 werewashed 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
1Department 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 oflethal 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 theEarly 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 theylikely 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:202Time: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-pelagiccoupling. 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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