Pliocene Of California Research Articles

Unique Feeding Morphology in a New Prognathous Extinct Porpoise from the Pliocene of California

Modern porpoises (Odontoceti: Phocoenidae) are some of the smallest cetaceans and usually feed near the seafloor on small fish and cephalopods [1-3]. Within both extinct and extant phocoenids, no evidence for specialized mandibular morphology has been documented [4-7]. Here we describe a new species of extinct porpoise, Semirostrum ceruttii, from the marine Pliocene San Diego (4.2-1.6 mega-annum, Ma) and Purisima (5-2.5 Ma) formations of California. The mandibles comprise a long, fused, and nearly edentulous prognathous symphysis, extending farther beyond the rostrum than in any known mammal. Phylogenetic analyses based on morphology reconstruct Semirostrum ceruttii as sister to extant (crown) porpoise species with moderate support. We describe the spectacularly preserved holotype specimen based on computed tomography (CT) scans, which allowed visualization of the elongate mental and accessory canals within the symphysis. The elongate canals are similar to those found in Rynchops birds [8] and were likely involved in sensory function. Oblique labial wear facets present on numerous small conical mandibular teeth posterior to the symphysis suggest regular contact with benthic substrate. The unique mandibular and dental characteristics, along with robust scapulae, sternum, and unfused cervical vertebrae, support the interpretation that this species employed a form of benthic skim feeding by using its mandible to probe for and obtain prey.

A new species of Neadmete (Neogastropoda) from the Pliocene of California

A new species of Neadmete (Neogastropoda) from the Pliocene of California

Cycles in Neogene paleoceanography and eustatic changes

A characteristic indicator of Antarctic and Arctic waters today is the sinistrally-coiled Globigerina pachyderma. By tracing this indicator back through the Neogene, it is possible to demonstrate major expansions of cold-water isotherms not only during the Quaternary, but also during the Middle Pliocene and the later Miocene. Expansions of cold-water isotherms of the Quaternary are correlated with the classic expansions of ice masses during the Pleistocene; those cold-water expansions of the Middle Pliocene and later Miocene suggest increases in ice masses with associated lowered sea levels, although perhaps not of the same magnitude as those of the Pleistocene. The Antarctic and Greenland ice masses were likely much more extensive during all of these colder cycles than now. Major cycles of expanded cold-water isotherms were almost certainly associated with eustatic reductions in sea level, that in turn produced marine regressions in paralic environments. Thus, there should be regressive cycles associated with the expansion of cold-water isotherms within the later Miocene, the Middle Pliocene, and those of the classic Quaternary. In the absence of complications due to variable rates of sedimentation and tectonism, shallow water depositional sites may show an Upper Miocene nonmarine phase or unconformity, a Lower Pliocene marine phase, a Middle Pliocene nonmarine phase or an unconformity, an Upper Pliocene marine phase, and a major regression at the beginning of the Quaternary. A re-evaluation of Neogene marine sections is suggested. It may be possible that the transgressive facies of the Calabrian of Italy correlates with the later Pliocene of California and is older than 3 × 10 6 years.

A new species of Boetica from the Pliocene of California

A new species of Boetica from the Pliocene of California

A New Gerrhonotine Lizard from the Pliocene of California

The specimen consists of the facial portion of a skull in fine-grained and apparently water-laid volcanic ash and split longitudinally through the palate. I have embedded the dorsal half of the specimen in plaster and prepared the dorsal surface of the skull. Until this was done, the specimen was thought to be a Gerrhonotus, but after preparation, the multiple scutes in the frontal area indicated that this was not the

Nimravides, a New Genus of Felidae from the Pliocene of California, Texas and Oklahoma

The Arnett local fauna from Ellis County, Oklahoma (see Kitts, 1957) includes two remarkably well preserved and complete felid lower jaws. Investigation has revealed that these specimens are very similar to and probably conspecific with material from the Higgins local fauna which has been referred to Machairodus Kaup (see Hesse, 1940) and material from the Black Hawk Ranch local fauna which has been referred to Pseudaelurus Gervais (see Macdonald, 1948). A study of the Arnett, Black Hawk Ranch and Higgins specimens reveals that they are certainly not referable to Machairodus and that, although they bear a number of marked resemblances to the lower jaw of Pseudaelurus , their generic separation from this genus is almost certainly justified. I should like to express my gratitude to Dr. Donald E. Savage of the University of California who allowed me complete access to the specimens in his charge and to Dr. J. R. Macdonald who permitted me to reproduce two figures from his paper on the Black Hawk Ranch carnivores. The plate was prepared by Mr. Irwin Gold. This study was supported by a grant from the faculty research fund of the University of Oklahoma. The following abbreviations are used: O.U.S.M.—J. Willis Stovall Museum of Science and History, University of Oklahoma; U.C.M.P.—Museum of Paleontology, University of California. All measurements are in millimeters. > Family FELIDAE Gray, 1821 > > Subfamily Nimravinae Trouessart, 1885 > > Nimravides gen. nov. > > (Figs. 1, 2; Plate I) Fig. 1 Nimravides thinobates (Macdonald). Type, U.C.M.P. No. 34513, right lower jaw fragment with P3 and M1; a, crown view; b, lateral view; ×½. (After Macdonald). Fig. 2 Nimravides thinobates (Macdonald). U.C.M.P. No. 34512, skull; a, palatal view. b, lateral view. ×½. (After Macdonald). Plate I Nimravides thinobates (Macdonald). a and b , O.U.S.M. No. 36-4-S13, left lower jaw; a , crown view of cheek …

A New Rana from the Pliocene of California

FOSSIL Anura have rarely been reported from the Pacific Coast states. Only a single extinct species (Bufo nestor Camp, 1917) has been described, and mention has been made of three others: Rana and Bufo sp. (Savage, 1951: 226) and the Recent Bufo boreas (Camp, op. cit.). Through the courtesy of Dr. Charles L. Camp, the author has been permitted to examine and describe a fossil Rana from the middle Pliocene of central California.

A New Mustelid Genus from the Pliocene of California

A New Mustelid Genus from the Pliocene of California

The Asiatic Genus Eomellivora in the Pliocene of California

The Asiatic Genus Eomellivora in the Pliocene of California

Note on "Cosomys" Wilson, from the Pliocene of California

Note on "Cosomys" Wilson, from the Pliocene of California

Cosomys, a New Genus of Vole from the Pliocene of California

Cosomys, a New Genus of Vole from the Pliocene of California

A New Pinniped from the Upper Pliocene of California

A New Pinniped from the Upper Pliocene of California