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The age of the Oso Member, Capistrano Formation, and a review of fossil crocodylians from California

Fossils from the late Miocene Oso Member of the Capistrano Formation in Orange County, California, are underreported in the scientific literature. Mitigation activities in the Oso Member have resulted in collections of fossils in museums. We provide a preliminary list of identified faunal elements from the Oso Member and determine its age using biostratigraphy. The presence of the fossil horse Dinohippus interpolatus allows us to constrain the age of the Oso Member to the early late Hemphillian (Hh3, 6.6–5.8 Ma). We provide a review of other Hemphillian terrestrial vertebrate sites from Southern California. Our age assessment for the Oso Member allowed us to recognize a significant temporal range extension for crocodylians on the Pacific Coast of the United States. Including the Oso Member, the fossil record of crocodylians in California is based on fragmentary material from 13 formations ranging from the Paleocene to the late Miocene (including seven Eocene units). Of these records, the Oso Member fossils represent the youngest record of fossil crocodylians in California. Fossil crocodylians from Orange County extend the record of crocodylians in California ~10 million years from the middle Miocene to the late Miocene.

New theropod fossils from the Upper Triassic Dockum Group of Texas, USA, and a brief overview of the Dockum theropod diversity

New records enrich the Late Triassic theropod assemblage of the Dockum Group of Texas. Here, five unpublished theropod specimens (TTU-P11175, TTU-P12531X, TTU-P12587X, TTU-P14786, TTU-P16789) are described, each represented by a single element and collected from various fossil localities of Garza County, Texas. Additionally, two previously described specimens (TTU-P10082, TTU-P10534), which were also recovered from Upper Triassic rocks of Garza County are revisited for additional remarks on their anatomy. These new theropod specimens increase the abundance and disparity of theropods in the Dockum terrestrial vertebrate fauna. Together, with confirmed theropod discoveries in other recent works, the newly evaluated specimens add to the long history of dinosaur research in the Dockum Group of Texas.

Western Association of Vertebrate Paleontology Annual Meeting: Program with Abstracts

The Program and Abstracts volume for the 2017 WAVP annual meeting held February 17-19, 2017 at Yavapai College, Prescott, Arizona.

Procerberus (Cimolestidae, Mammalia) from the Latest Cretaceous and Earliest Paleocene of the Northern Western Interior, USA

Three species of the cimolestid Procerberus are currently recognized in the northern North American Western Interior in latest Cretaceous and earliest Paleocene (Puercan North American Land Mammal Age) faunas: P. formicarum, P. andesiticus, and P. grandis. Analysis of a new topotypic sample of P. formicarum from the Bug Creek Anthills locality provides an estimate of the range of variation of its postcanine dentition. The three currently recognized species occur in Puercan 1 (Pu1) interval zone faunas, but two other occurrences indicate that the genus originated and initially diversified prior to the Cretaceous/Paleogene boundary. Rare occurrences at several localities and entries in faunal lists suggest even greater taxonomic diversity. Limited evidence suggests continued diversification in the later Puercan and possible survival of the genus into the Torrejonian. Procerberus grandis or a closely related species may be a sister group of primitive taeniodonts.

A new Early Pliocene record of the toothless walrus Valenictus (Carnivora, Odobenidae) from the Purisima Formation of Northern California

The walrus (Odobenus rosmarus) is a large tusked molluskivore that inhabits the Arctic and is the sole living member of the family Odobenidae. In contrast to the modern walrus, extinct walruses lived in temperate and even subtropical climates as far south as Baja California and Japan in the Pacific, and Florida and Morocco in the Atlantic. Multispecies walrus assemblages are now documented from several localities in the North Pacific, the center of origin for the family. The genus Valenictus is a toothless dense-boned walrus reported from several localities in southern California and Baja California. An isolated astragalus from lower Pliocene (5.33–4.89 Ma, Zanclean correlative) sediments of the Purisima Formation of northern California (Santa Cruz County, California) matches the highly derived morphology of Valenictus chulavistensis, and is identifiable as Valenictus sp. This specimen is the first record of Valenictus from the Purisima Formation and the first from northern California.

A juvenile of the multiple-tooth-rowed reptile Labidosaurikos (Eureptilia, Captorhinidae, Moradisaurinae) from the Lower Permian of north-central Texas

Harvard University Museum of Comparative Zoology (MCZ) 1352 is a partial maxillary toothplate of a basal reptilian from the Lower Permian of Baylor County, north-central Texas. The specimen displays the straight rows of teeth characteristic of the subfamily Moradisaurinae (family: Captorhinidae) and is nearly identical in shape to the maxilla of Labidosaurikos meachami. Larger, more mesial individual teeth conform to the dental pattern previously determined for adults of the genus. Adults of L. meachami are known to possess six maxillary tooth rows, whereas MCZ 1352 has only five. Although only a partial specimen, it appears MCZ 1352 is most likely a juvenile specimen of L. meachmi. If correct, the comparative sizes suggest isometric growth of this element. The orientation of the lingual-most row of teeth, and the five as opposed to six maxillary tooth rows, suggest either new tooth rows may move labially during development or bone growth and remodeling occur lingually, resulting in the development of a margin of maxillary bone between the fifth row and the lingual edge.