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15 recordsLinked to original sources
USGS2010

Rodents and lagomorphs (Mammalia) from the Hemphillian (late Miocene) of Utah

Four species of rodents (two heteromyids and two cricetids) and one lagomorph are identified from the late Tertiary Sevier River Formation of Utah. The heteromyids include a new genus and species of heteromyine, Metaliomys sevierensis, which is intermediate in morphology between the Clarendonian and early Hemphillian Diprionomys Kellogg and the extant genera Liomys and Heteromys. A single specimen is referred to Diprionomys sp., cf. D. minimus (Kellogg). The cricetid Paronychomys lemredfieldi Jacobs is known from the Hemphillian of Arizona. The second cricetid is referred to a new genus Basirepomys. Peromyscus pliocenicus Wilson from the Hemphillian of California is designated as the type species of the new genus, to which the new species B. robertsi from Utah is referred. Basirepomys is viewed as intermediate between Peromyscus and the basal neotomyine Repomys May from the late Hemphillian and Blancan. The only lagomorph in the fauna is Hypolagus vetus (Kellogg). Four of the taxa recognized from the Sevier River Formation (Diprionomys, Paronychomys lemredfieldi, Basirepomys, and Hypolagus vetus) are elsewhere known from the Hemphillian of North America. However, it is not possible at this time to determine whether the fauna is early or late Hemphillian. ?? 2010 by the Society of Vertebrate Paleontology.

Journal of Vertebrate Paleontology↗
USGS2006

Sexual dimorphism of the internal mandibular chamber in Fayum Pliohyracidae (Mammalia)

An internal mandibular fenestra and chamber are found in many fossil hyracoids. The internal mandibular fenestra is located on the lingual surface of the mandibular corpus and opens into a chamber within the mandible. The mandibular chamber is maximally developed in late Eocene Thyrohyrax meyeri and early Oligocene Thyrohyrax domorictus from the Fayum Province of Egypt. The function of this chamber is unknown as it is not found in extant hyraxes, nor is it known to occur in any other mammal. In Thyrohyrax, this feature appears to be sexually dimorphic because it is confined to roughly one half of the specimens that otherwise cannot be separated by dental characteristics or measurements. It has been suggested that the chamber is found in females based on the presumed distribution of this character in other fossil hyracoids. Fossils from Fayum Quarry L-41, preserving the sexually dimorphic anterior dentition, show that, in Thyrohyrax meyeri and Thyrohyrax domorictus, the internal mandibular chamber is found in males. In Thyrohyrax litholagus, an internal mandibular fenestra and inflated mandibular chamber occurs in males whereas females show the variable presence of an internal mandibular fossa or fenestra but lack an expanded chamber. Other genera show differing patterns of sexual variation in which some Fayum hyracoids have an internal mandibular fenestra in both sexes but with the greatest development of the mandibular chamber occurring in males. We review functions proposed for the internal mandibular chamber and suggest that it housed a laryngeal air sac that may have had a vocal function by acting as a resonating chamber. ?? 2006 by the Society of Vertebrate Paleontology.

Journal of Vertebrate Paleontology↗
USGS2005

Taxonomic revision and stratigraphic provenance of 'Histiophorus rotundu' Woodward 1901 (Teleostei, Perciformes)

Until recently, † Histiophorus rotundus Woodward 1901, was known from a single, poorly preserved rostrum from the Tertiary phosphate beds near Charleston, South Carolina, an area from which many fossils have been described. The specimen is relatively featureless externally; its internal anatomy is unknown and the documentation of its geological provenance was poor. In an earlier revision the species was transferred to the fossil billfish genus † Xiphiorhynchus Van Beneden, 1871. Here we confirm this designation, supported by new morphological studies of the holotype, recently found specimens of † Xiphiorhynchus rotundus (Woodward, 1901), and the stratigraphic record of † Xiphiorhynchus . The systematic paleontology we present is a contribution to the taxonomic revision of billfishes world-wide. Because the holotype is heavily phosphatized and the type locality was vaguely described, we discuss the geology of the phosphate mining districts of the Charleston region. Based on our studies, we can narrow the possible age of the holotype to late Oligocene or early Miocene. We suggest † X. rotundus was extinct by the Burdigalian.

Journal of Vertebrate Paleontology↗
USGS1990

New Washakiin primates (Omomyidae) from the Eocene of Wyoming and Colorado, and comments on the evolution of the Washakiini

Two new species of washakiin omomyids occur in deposits of early Bridgerian age. Shoshonius bowni , sp. nov., from the Aycross Formation, Absaroka Range, Wyoming, differs from S. cooperi in having enlarged conules on the upper molars and a second metaconule, features convergent with Washakius insignis. Washakius izetti , sp. nov., from the Green River Formation, Piceance Creek Basin, Colorado, is the most primitive known species of Washakius , showing incipient development of features present in the later W. insignis and W. woodringi. Washakius , cf. W. izetti occurs in the early Bridgerian of the Huerfano Basin. W. izetti is closely related to Utahia kayi , a. washakiin possibly related to Stockia. Hemiacodon , sometimes included in the Washakiini, is probably more closely related to the Omomyini. Stockia is distinct from Omomys and is questionably included in the Washakiini, of which Loveina is the stem taxon. More advanced washakiins form two groups between which there was significant parallel evolution in dental morphology. One group includes Washakius, Dyseolemur, Utahia , and possibly Stockia , and is characterized by development of an open talonid notch before the consistent appearance of metastylids. The other group consists of Shoshonius , where the establishment of metastylids preceded the full opening of the talonid basins.

Journal of Vertebrate Paleontology↗
USGS1998

A problematic early tetrapod from the Mississippian of Nevada

We report here the discovery of a new taxon of Paleozoic tetrapod from the Late Mississippian of Nevada (330–340 Ma). It has a unique vertebral column with principal centra having vertical anterior and posterior faces, ventrally incomplete accessory centra located antero-dorsally in each centrum, and enlarged presacral/sacral vertebrae. The head and pectoral girdle were not preserved but the large femur, robust pelvic girdle and enlarged sacral vertebrae possibly indicate a terrestrial mode of life. This new form significantly extends the western geographic range of known Mississippian tetrapods. It presents a mosaic of primitive and derived features, indicating that continued revision of traditional accounts of vertebral homology and the early diversifications of Paleozoic tetrapods will be necessary.

Journal of Vertebrate Paleontology↗
USGS2011

New information on the braincase of the North American therizinosaurian (Theropoda, Maniraptora) Falcarius utahensis

Many disarticulated bones from multiple individuals of a primitive therizinosaurian, referred to Falcarius utahensis , were found in the paucispecific Crystal Geyser bonebed in the Lower Cretaceous Cedar Mountain Formation of eastern Utah. To date, more than 2000 specimens from this species have been excavated. Included in this collection are two partial braincases, one of which is designated the holotype. Here we describe the braincase morphology of Falcarius utahensis . These specimens help establish the primitive cranial condition for the Therizinosauria and further substantiate intraspecific and contralateral braincase pneumatic variation in theropods. When combined with new observations on the cranial remains of the therizinosaurid Nothronychus mckinleyi derived from computed tomographic (CT) scans, the braincase morphology of Falcarius clarifies several evolutionary trends within the Therizinosauria and establishes a suite of synapomorphies for the Therizinosauridae. Trends within the clade include increased basicranial pneumatization (the development of a basisphenoid bulla and loss of external subcondylar recesses), anterior deflection of the supraoccipital, and the reduction of points of origin of the craniocervical musculature, associated with the loss of discrete basipterygoid processes, probably due to incorporation of these structures into the expanded hyperpneumatic bone. Finally, CT scans reveal a complete, nearly avian, inner ear with bird-like semicircular canals and a long cochlea indicating broad frequency discrimination.

Utah↗
USGS2007

Velafrons coahuilensis , a new labeosaurine haddrosaurid (Dinosauria: Ornithopoda) from the Late Campanian Cerro del Pueblo formation, Coahuila, Mexico

A new lambeosaurine hadrosaurid, Velafrons coahuilensis , is described as the first lambeosaurine from the Cerro del Pueblo Formation of Coahuila, Mexico, and the first lambeosaurine genus to be named from North America in more than 70 years. Although the holotype specimen is a juvenile individual—as evidenced by its incomplete crest development and relative size compared to other North American lambeosaurines—ontogeny independent autapomor-phies have been identified including quadrate with narrow quadratojugal notch and a postorbital with well developed, dorsally positioned squamosal process. Additionally, this taxon is unique in that the prefrontal is not dorsally deflected and anteroposteriorly expanded as in other lambeosaurine taxa of its size, but rather retains the frontal-prefrontal “clamp” present in smaller individuals of other taxa. Phylogenetic analysis places Velafrons in a polytomy with numerous other fan-crested lambeosaurines. The crest structure of Velafrons more closely resembles that of Corythosaurus and Hypacrosaurus because it possesses an anteriorly projecting nasal process over the dorsal premaxilla process. Biogeo-graphically, Velafrons is one of three distinct hadrosaurids known from approximately 73.5 Ma—two lambeosaurines and one hadrosaurine—all restricted to the southern region of the Western Interior Basin of North America.

Coahuila↗
USGS2004

Chondrichthyans from the Pennsylvanian (Desmoinesian) Naco Formation of central Arizona

Teeth, spines, and dermal denticles of chondrichthyans are reported from the Middle Pennsylvanian (Desmoinesian) Naco Formation of central Arizona. The most common elements are crushing teeth of the cochliodont Deltodus angularis , less common are teeth of D. sublaevis , Venustodus leidyi , Lagarodus angustus , “ Cladodus ” occidentalis , Petalodus ohioensis , Orodus sp., and Hybodontoidea. Fin spines of Acondylacanthus sp., Amelacanthus sp., and Physonemus sp., and the dermal denticle Petrodus patelliformis are also present. The material of Venustodus leidyi shows for the first time that this animal was heterodont, having arched anterior teeth with a v-shaped profile grading posteriorly into lower crescentic, and finally flattened teeth. Lagarodus angustus is shown to have at least three tooth morphotypes, and a new tooth arrangement is proposed in which small anterior teeth are replaced posteriorly by large crushing teeth arranged in whorls. This fauna is similar to others in New Mexico, Colorado, and Ohio and constitutes a western extension of such faunas in North America. In addition, the presence of Deltodus sublaevis and Lagarodus angustus documents a range extension from a known European distribution, reinforcing the cosmopolitan nature of chondrichthyan faunas at this time.

Journal of Vertebrate Paleontology↗
USGS2016

A Bohemian-type Silurian (Wenlockian) pelecypod faunule from Arctic Canada

The pelecypod genera Slava and Rhombopteria are reported for the first time from Canada, where they occur in a limestone concretion within the Cape Phillips Formation, Cornwallis Island, Arctic Archipelago. These genera are characteristic of Silurian rocks in Bohemia, Czechoslovakia. Graptolites from the same concretion indicate the Monograptus ludensis Zone (uppermost Wenlockian); this age is substantiated by associated conodonts, trilobites, vertebrates, and pelecypods but with less precision. It is difficult to explain the occurrence of Slava and Rhombopteria in the middle of Laurentia on the basis of some map reconstructions of the Wenlockian world. The Canadian material of Slava novaterra n. sp. and Rhombopteria cf. R. mira (Barrande) is described. Leptodesma ( Leptodesma ) sp. A and an indeterminate grammysiid pelecypod from the same concretion are illustrated. Information is provided to show that Newsomella Foerste, from Wenlockian–Ludlovian rocks of Illinois, Wisconsin, and Tennessee, is not a subgenus of Rhombopteria Jackson.

Journal of Paleontology↗
USGS1997

Late quaternary regional geoarchaeology of Southeast Alaska Karst: A progress report

Karst systems, sea caves, and rock shelters within the coastal temperate rain forest of Alaska's Alexander Archipelago preserve important records of regional archaeology, sea level history, glacial and climatic history, and vertebrate paleontology. Two 14C AMS dates on human bone discovered in a remote cave (49-PET-408) on Prince of Wales Island document the oldest reliably dated human in Alaska to ca. 9800 B.P. A series of 14C AMS dates from cave deposits span the past 40,000 years and provide the first evidence of Pleistocene faunas from the northwest coast of North America. Other discoveries include sea caves and marine beach deposits elevated above modern sea level, extensive solution caves, and mammalian remains of species previously undocumented within the region. Records of human activity, including cave art, artifacts, and habitation sites may provide new insights into the early human colonization of the Americas. ??1997 John Wiley & Sons, Inc.

Alaska↗
USGS2019

Fluvial sedimentary history of Arlington Canyon, Channel Islands National Park, California

Arlington Canyon, in the northwest part of Santa Rosa Island, Channel Islands National Park, California, has been the setting for important scientific discoveries over the past half century, including the oldest human remains in North America, several vertebrate fossil sites, and purported evidence of a catastrophic extinction event at the end of the Pleistocene. The canyon is filled with alluvial sediments that date to between 16.4 and 1.1 ka (thousands of calibrated years before present), representing accumulation that occurred primarily in response to rising sea levels during the late Pleistocene and Holocene. The deposits are laterally discontinuous, exhibit a high degree of sedimentary complexity, and contain evidence of past climates and environments, including fossil bones, burned plant macrofossils, and invertebrate microfossils. Here, we show that it is critical to view the observations, data, and conclusions of scientific studies conducted in the canyon within this larger context so that localized facets of the spatially and temporally extensive alluvial deposits are not misinterpreted or misrepresented. By improving the baseline understanding of processes and drivers of sediment accumulation in Arlington Canyon, we hope to offer a solid foundation and better underpinning for future archeological, paleontological, and geochemical studies here and throughout the northern Channel Islands.

California↗
USGS1978

Dating Quaternary faults in the southwestern United States by using buried calcic paleosols

Calcareous soils are widespread on upper Pliocene to upper Pleistocene unconsolidated surflcial deposits in semiarid portions of the southwestern United States. Where these soils are related to faults, the soils may provide a means for quantitatively estimating timing and amounts of Quaternary faulting. Soil age estimates are based on the amount of pedogenic CaCO 3 (g/cm 2 -soil column) that has accumulated from soil processes, whereas rates of calcic-soil formation were calibrated by the K-Ar dating method, tephrochronology, vertebrate paleontology, and regional soil studies. The County Dump fault, west of Albuquerque, N. Mex. cuts a 500 000-yearold datum, the Llano de Albuquerque. The downdropped block of this fault contains a sequence of faulted younger deposits and intercalated calcic paleosols. Soil ages, and hence fault ages, can be calculated by measuring the total pedogenic calcium carbonate content in a section of buried paleosols and by using an independently established maximum soil formation rate of 0.35 g CaCO 3 • cm -2 • 10 -3 yr -1 for the Albuquerque area. This particular fault segment has had four discrete episodes of movement in the past 500 000 yr, the most recent of which occurred about 20000 yr B.P. Recurrence intervals on the segment are 90 000-190 000 yr, but the composite recurrence interval for all fault movements in this area may be less by several orders of magnitude. This technique of quantifying soil properties and calculating ages of relict soils can be used to estimate ages of Quaternary deposits and associated surfaces, to correlate such features over broad regions, and to analyze regional trends in calcic-soil formation.

New Mexico↗
USGS2016

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

Heavily tuberculated glyptosaur osteoderms were collected in an active limestone quarry in northern Berkeley County, South Carolina. The osteoderms are part of a highly diverse late Paleocene vertebrate assemblage that consists of marine, terrestrial, fluvial, and/or brackish water taxa, including chondrichthyan and osteichthyan fish, turtles (chelonioid, trionychid, pelomedusid, emydid), crocodilians, palaeopheid snakes, and a mammal. Calcareous nannofossils indicate that the fossiliferous deposit accumulated within subzone NP9a of the Thanetian Stage (late Paleocene, upper part of Clarkforkian North American Land Mammal Age [NALMA]) and is therefore temporally equivalent to the Chicora Member of the Williamsburg Formation. The composition of the paleofauna indicates that the fossiliferous deposit accumulated in a marginal marine setting that was influenced by fluvial processes (estuarine or deltaic). The discovery of South Carolina osteoderms is significant because they expand the late Paleocene geographic range of glyptosaurines eastward from the US midcontinent to the Atlantic Coastal Plain and provide one of the few North American records of these lizards inhabiting coastal habitats. This discovery also brings to light a possibility that post-Paleocene expansion of this group into Europe occurred via northeastward migration along the Atlantic coast of North America.

South Carolina↗