Megamouth Shark Morphometrics
Krak and Shimada use geometric morphometrics to reconstruct extinct megamouth shark tooth rows
Allonia from the middle Cambrian Wheeler Formation of Utah
Foster, Howells and Sroka report new details of early sponge-like animals from a spectacularly-preserved specimen from the Cambrian of western Utah.
Death Valley Devonian Acanthodians
A new stem chondrichthyan fauna from the Lost Burro Formation of California by Carole J. Burrow and David K. Elliot.
Toxochelys latiremis Cope, 1873
First report of this turtle from the Cretaceous of Alabama, USA by Andrew Gentry and Jun Ebersole.
Calliovarica oregonensis Hickman
A new species of chilodontid gastropod from the Eocene of Oregon, USA by Carole S. Hickman.
An EPICC contribution!
Annotated list of the Cenozoic marine formations of the Pacific Northwest by Liz Nesbitt.
Use of machine learning to classify extant apes!
Monson et al. apply machine learning using dental morphology to classify extant apes and shed light on the chimpanzee-human last common ancestor.
New subadult skull specimen of Euclastes wielandi Hay, 1908 from the Cretaceous of New Jersey, USA!
New study of a subadult skull by P. Ullmann, Z. Boles and M. Knell provides insights into the cranial morphology and intraspecific variation in the Cretaceous pan-cheloniid turtle Euclastes wielandi.
Cimolestids (Mammalia) from the Paleocene of Montana!
New report on Puercolestes and Betonnia, two cimolestids from the early Paleocene (Puercan) of northeastern Montana, U.S.A. by William A. Clemens.
Eocene cassid gastropods from North America!
A reassessment by Richard Squires of Eocene warm-water cassid gastropods (Family Cassidae) from North America and implications for their paleogeographic distribution and faunal turnover following the Paleocene-Eocene Thermal Maximum.
Late Eocene elasmobranchs from Aiken County, South Carolina, USA!
Cicimurri and Knight describe new material of sharks and rays (elasmobrachs) from the Dry Branch Formation of Aiken County, South Carolina USA.
Nestling-sized hadrosaurine crania from the Late Cretaceous of Montana!
Wosik et al. describe new cranial remains of hadrosaurine nestlings from the Late Cretaceous Hell Creek Formation, Montana, USA, with analysis of cranial ontogeny in Edmontosaurus annectens.
Miocene macropaleontology of the Caldecott Tunnel fourth bore excavation, Berkeley Hills, CA, USA!
Powell et al. describe Miocene marine macrofossils recovered from the fourth bore excavation of the Caldecott Tunnel in the Berkeley Hills, Oakland, CA, USA.
New protocol for differentiating leporids from the late Quaternary of southern California, USA!
Fox et al. propose new protocol using dental morphology for identifying late Quaternary leporids from southern California with remarks on lagomorphs from Rancho La Brea's Project 23!
A new drepanosauromorph from the Chinle Formation of Petrified Forest National Park, Arizona, USA!
Gonçalves and Sidor describe the new Triassicdrepanosauromorph genus and species,Ancistronychus paradoxus, from the Chinle Formation of the Petrified Forest National Park, Arizona, USA!
Epiplastral shape and geographic variation of Echmatemys from the Eocene of Utah!
Heather F. Smith et al. analyze epiplastral shape and geographic variation in thegeoemydid turtle, Echmatemys,from the Eocene Uinta Basin , Utah, USA.
The new species Lyropecten terrysmithae from the Miocene of central California!
Powell et al. describe and name a new pectinid, Lyropecten terrysmithae , from the Miocene of California in honor of Dr. Judy Terry Smith for her work on California and Mexican invertebrate paleontology.
Faunal change in Cretaceous endemic bivalves of the northeast Pacific!
Richard Squires reports on the faunal change in Cretaceous shallow-marine endemic bivalve genera/subgenera of the northeast Pacific region.
New report of the fossil otolith species, Equetulus silveraldensis n. comb., from the Oligocene of the Gulf Coastal Plain, USA!
Stringer et al. describe the first record of the teleostean fish otolith, Equetulus silveraldensis n. comb., from the Oligocene of Alabama, USA, and its enigmatic geographic distribution.
New dinosauromorph body fossils from the Petrified Forest National Park, Arizona, USA!
Adam Marsh and William Parker describe new dinosauromorph specimens from the Chinle Formation Petrified Forest National Park and provide a global biostratigraphic review of Triassic dinosauromorphs.
Checklist of Paleogene-Neogene marine Mollusca from California!
Groves and Squires present an annotated catalog of Paleogene-Neogene Mollusca from California since Keen and Bentson's 1944 checklist.
New mid-Miocene equids from the Cajon Valley Formation, CA!
Stoneburg et al. describe new fossil horse remains from the mid-Miocene of San Bernardino County, CA.
New fossil fishes from South Carolina, USA!
Cicimurri et al. report on a diverse fauna of Oligocene fishes from the Ashley Formation of South Carolina, with description of a new catshark species, Scyliorhinus weemsi.
Changes in southern California oyster paleocommunity structure over the last 3.6 million years!
Bonuso et al. use digitized data from the EPICC TCN and other sources to reconstruct Late Cenozoic oyster communities in southern California, USA.
The earliest Ancistrolepis, from the early Eocene of Simi Valley, California, USA
Squires updates our knowledge of the oldest species of this extant buccinid gastropod genus
The first Cretaceous fish otolith assemblage from the Arkadelphia Formation of Arkansas, USA!
Stringer and Sloan describe the first otolith assemblage from the Late Cretaceous of Arkansas and its implications for our understanding of the Western Interior Seaway.
Pteriomorph bivalves from the Eocene-Oligocene Keasey Formation in Oregon, USA!
Hickman describes the pteriomorph bivalves from the Eocene-early Oligocene Keasey Formation in Oregon, recognizing a new peri-seep biotope association.
Volume 40, Issue 1, 2023
Articles
The dentition of the extinct megamouth shark, Megachasma applegatei (Lamniformes: Megachasmidae), from southern California, USA, based on geometric morphometrics
Megachasma applegatei is an extinct megamouth shark (Lamniformes: Megachasmidae) commonly found in late Oligocene‒early Miocene marine deposits of the western USA, that is known only from isolated teeth exhibiting odontaspidid tooth design. In this study, we investigated the tooth morphometry of the extant megamouth shark (Megachasma pelagios) and smalltooth sandtiger (Odontaspis ferox: Odontaspididae) to aid in the reconstruction of the dentition of M. applegatei based on the tooth morphometry of 207 isolated fossil teeth from the lower Miocene Jewett Sand of southern California. Our landmark-based geometric morphometric analyses show that M. applegatei not only possesses a wider morphological range of teeth than M. pelagios, but also has morphological variation that can be corresponded to different tooth types in O. ferox, forming a unique heterodont dentition typical for macrophagous lamniform sharks known as the ‘lamnoid tooth pattern’. Therefore, our study suggests that the dentition of M. applegatei could have also exhibited the lamnoid tooth pattern. In order to reconstruct the dentition of M. applegatei, specific tooth specimens plotted on the morphospace of M. applegatei were selected by identifying teeth of specific tooth types in the corresponding morphospaces of M. pelagios and O. ferox. However, because the total number of teeth per each dental series cannot be ascertained, we generated three sets of reconstructed dentition for M. applegatei. The first set modeled the dentition of O. ferox, the second set representing an intermediate form between O. ferox and M. pelagios, and the third set mimicking the dentition of M. pelagios, with the assumption that the true dental pattern for M. applegatei lies somewhere between the first and third tooth sets, possibly close to the second set. This study represents the first case of using geometric morphometrics to reconstruct the dentition of an extinct shark.