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.
First leatherback sea turtle (family Dermochelyidae) from the Mio-Pliocene Purisima Formation of California!
Bailey Fallon and Bobby Boessenecker describe the first leatherback sea turtle, cf. Psephophorus, from the lower Pliocene Purisima Formation of California, USA.
The Miocene Mascall vertebrate fauna revisited!
An excellent update of the vertebrate fauna and chronostratigraphy of the Miocene type Mascall Formation, John Day Basin, Oregon, USA by Kaitlin Clare Maguire, Joshua Samuels, and Mark Schmitz.
Toxochelys latiremis Cope, 1873
First report of this turtle from the Cretaceous of Alabama, USA by Andrew Gentry and Jun Ebersole.
Program and abstracts for the 52nd annual meeting of the Western Association of Vertebrate Paleontologists held at Dixie State University in St. George, Utah, USA.
Calliovarica oregonensis Hickman
A new species of chilodontid gastropod from the Eocene of Oregon, USA by Carole S. Hickman.
Late Triassic vertebrates from the Dockum Group of Texas!
New apomorphy-based identifications of vertebrates from the Late Triassic Dockum Group of Texas by Lessner et al.
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.
NAPC 2019 Field trip guide to the Ediacaran-Cambrian transition in the southwestern USA!
Field trip guide to the Ediacaran-Cambrian transition led by E. Smith, L. Tarhan and L. Nelson for the 2019 North American Paleontological Convention (NAPC).
Late Cretaceous endemic shallow-marine gastropods of the northeast Pacific!
Biodiversity and faunal changes in Late Cretaceous northeast Pacific gastropods by Richard L. Squires.
NAPC 2019 field trip guide to the geology and paleontology of Miocene formations in southern California!
Katharine Loughney and Tara Smiley's NAPC 2019 field trip guide to the geology and paleontology of the Miocene Barstow, Crowder, and Cajon Valley formations of southern California.
Program and Abstracts for the 11th North American Paleontological Conference!
Program and Abstracts for the 11th North American Paleontological Conference (NAPC) hosted by University of California, Riverside June 23-27, 2019.
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!
New limpets from the Miocene of southern California, USA!
Charles Powell and Daniel Geiger describe and name two new limpet species, Scelidotoma aldersoni n. sp. and Fissurella? stantoni n. sp. from the Miocene of southern California, 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 presentan 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.
Powell and Houart report on Califrapana, a new genus of muricid gastropod from the Oligo-Miocene of CA and Baja CA, Mexico!
Taphonomic bias in collections of horse phalanges from the Miocene Barstow Formation and Pleistocene Rancho La Brea of California, USA!
New early Oligocene records of the insectivorous mammal genus Sinclairella (Apatemyidae) from the John Day Formation, Oregon, USA!
New report on proboscideans from the Miocene Siwalik Group of Pakistan!
First mosasaurine collected from the Breien Member of the Hell Creek Formation in North Dakota, USA!
Volume 38, 2021
This checklist is a sequel to the one published by A. Myra Keen and Herdis Bentson in 1944 and is an alphabetical listing of California marine Paleogene–Neogene mollusk species or subspecies described and/or figured in the published literature spanning the interval of 1944 through 2020. The original data are given for each species and subspecies of bivalves, gastropods, chitons (polyplacophorans), scaphopods, and cephalopods. Where detected, formation names, ages, taxonomy, systematics, and specimen disposition were corrected. A total of 559 genera and 1,698 species/subspecies were tabulated, with the bivalves and gastropods being the most abundant taxa. Bivalve and gastropod diversity steadily built up during the Paleocene, nearly doubled during the Eocene warm time, declined greatly during the cool time of the Oligocene, rebounded to its highest peak in the Miocene and then declined slightly during the Pliocene. The other classes represented only minor faunal components. Chitons were only reported from the Pliocene, and cephalopods had their highest diversity during the Paleocene and Eocene. Bivalve genera having the highest diversity are: Glycymeris, Macoma, Mactromeris, Nuculana, and Tellina. Gastropod genera having the highest diversity are Cancellaria and Turritella. It is very likely that the Turritella species/subspecies complex has been significantly overnamed. The high point of research productivity of published reports on California Paleogene-Neogene mollusks was in 1990–1994, and a significant decline occurred in 1995–1996, following the closure of the Menlo Park USGS Paleontology and Stratigraphy facility. An overall decline in productivity has continued, with noticeable upticks in 2003 and in recent years.
New remains of middle Miocene equids from the Cajon Valley Formation, San Bernardino National Forest, San Bernardino County, California, USA
New material of three equids is described from the middle Miocene Cajon Valley Formation in San Bernardino National Forest, San Bernardino County, California. The material includes teeth of Archaeohippus mourningi, Scaphohippus sumani, and Parahippus brevidens. Scaphohippus intermontanus is considered a junior subjective synonym of S. sumani. Parahippus brevidens is identified from an upper molar that closely resembles the morphology of the holotype as well as referred specimens of Pa. brevidens from the Mascall Formation in Oregon and the Temblor Formation in California. The presence of Pa. brevidens in the Cajon Valley Formation represents a geographic range extension for the taxon of over 400 km. Interesting ecological implications emerge for the Cajon Valley Formation when compared to the nearby Barstow Formation, including the presence of chalicotheres and apparent lack of Hypohippus affinis and Megahippus mckennai.
- 1 supplemental ZIP
Califrapana: a new genus of California and Bája California late Oligocene to early Miocene muricids previously attributed to the genus Rapana (Mollusca: Gastropoda: Muricidae)
Califrapana n. gen., is proposed for California late Oligocene to early Miocene muricids attributed previously to the possibly Paleocene to modern western Pacific and Indian oceans genus Rapana. Four fossil species have been assigned to Rapana in the eastern Pacific. One of these species, R. perrini Clark and Arnold (1923), should be placed in another genus, the other species Purpura vaquerosensis Arnold (1907), R. imperialis Hertlein and Jordan (1927), and R. serrai Wiedey (1928) are synonymized here with the morphologically variable species Califrapana vaquerosensis n. comb. We confirm C. vaquerosensis is an index fossil for the lower and middle “Vaqueros” California provincial molluscan stage of late Oligocene to early Miocene age in southern California and Bája California, México, although the lack of numerical dating and the misuse of lithostratigraphic and biostratigraphic names had made that difficult to determine. Califrapana is distinguishable from similar genera by 1) its heavier shell, 2) an aperture that is pointed at its anterior and posterior ends, 3) more numerous fine to coarse spiral cords on the ultimate whorl, 4) less numerous nodes at the top of the ultimate whorl, which are commonly larger and more pronounced, and 5) the siphonal fasciole, which is large and broad, with a large, open channel.
Taphonomic bias in collections of horse phalanges from the Barstow Formation (Miocene) and Rancho La Brea (Pleistocene) of California, USA
Isolated equid phalanges are relatively common finds in the Barstow Formation (Miocene, 19 to 13 million years ago, southern California), but anecdotal observations suggested that not all positions (proximal, middle, and distal/ungual) of the primary digit (digit III) are recovered with equal frequency. Our sample includes primarily surface-collected phalanges from the Barstow Formation, which we compare with phalanges of Pleistocene horses from Pit 3 and Pit 77 from Rancho La Brea (Los Angeles, California). The null hypothesis is that the three positions of phalanges should be equally common. Our Barstow sample includes 228 proximal, 151 middle, and 36 distal phalanges. A chi-square test (p<0.001) is consistent with preservation bias in phalangeal frequency for the full Barstow Formation sample, and this pattern generally holds within sub-samples by locality or depositional environment. Pit 3 of La Brea produced 163 proximal, 144 middle, and 103 distal phalanges. A chi-square test with correction for multiple comparisons suggests that proximal and middle phalanges are preserved with statistically equal frequency (p=0.278) whereas distal phalanges are less common (p<0.001). For Pit 77, there are 54 proximal, 55 middle, and 51 distal phalanges; the chi-square test finds that all three types are equally common (p=0.922). Overall, differences in physical properties between phalangeal positions, such as surface area, density, shape, and size, could influence preservation within each environment. The observed differences between Barstow and La Brea might be caused by variations in depositional environment that influence the surface exposure time of fossils and disarticulation pre-burial, as well as by differences in the size of the horses at each locality. We suggest that when permitted by sample size, it is desirable to distinguish unguals from other phalanges when analyzing taphonomic patterns in the fossil record.
- 2 supplemental files
Apatemyidae are a rare and enigmatic group of small insectivorous mammals that lived in North America and Europe in the Paleogene. The last known apatemyids in North America are two species in the genus Sinclairella, known from sites in the Great Plains and Florida. Here, I formally describe an upper second molar and lower incisor of the apatemyid, Sinclairella dakotensis, from the incredibly well-studied Turtle Cove Member of the John Day Formation in Oregon. These early Arikareean age specimens represent the first records of the family west of the Rocky Mountains. Sinclairella dakotensis filled a ‘woodpecking’ niche unlike any other mammal known from the region, and its co-occurrence with a number of forest-adapted mammal species is consistent with previous interpretations of environments at the time having been dominated by woodlands.
Over the years a diverse assemblage of proboscidean remains has been recovered from the Lower to Upper Siwalik Subgroups of Pakistan and India. This article reports newly discovered dental material of tri- and tetralophodont proboscideans that includes cf. Paratetralophodon hasnotensis and Choerolophodon sp., and a Gomphothere gen. et sp. indet., recently collected from late middle to late Miocene localities of the Pakistani Siwalik Group, with a brief history of these species. The partial premolar of cf. Pa. hasnotensis is described for the first time from the Siwalik Group, recovered from the Dhok Pathan Formation, and the specimens reported herein are the latest to be described after a 38-year gap from previously described material for this species. A preliminary survey of the literature and previously described material of Siwalik species suggests a revision of Siwalik Group proboscideans is much needed.
The first in situ collection of a mosasaurine from the marine Breien Member of the Hell Creek Formation in south-central North Dakota, USA
The upper Maastrichtian Breien Member situated within the lower portion of the Hell Creek Formation in south-central North Dakota records one of the last transgressions of the Western Interior Seaway (WIS) during the terminal Cretaceous. A fragmentary articular-prearticular complex and isolated vertebra belonging to a mosasauroid were recovered in 2016 from sandstones and mudstones deposited in a nearshore marine paleoenvironment within the southern arm of the bisected WIS. The medially-rotated retroarticular process on the articular-prearticular complex, the shape of the glenoid fossa, along with the morphology of the isolated vertebra, facilitate a conservative referral to a large-bodied mosasaurine such as Mosasaurus or Prognathodon. The rocks of the Breien Member provide paleontologists a unique glimpse of intracontinental marine ecosystems immediately prior to the end of the Cretaceous Period. This discovery provides additional evidence that the latest Maastrichtian marine fauna is a continuation of the fauna preserved in the underlying Fox Hills Formation and that the marine faunal turnover that gave rise to the subsequent Cannonball Sea fauna recorded in Paleocene rocks in North Dakota occurred at the Cretaceous-Paleogene boundary.
Reconstructing oyster paleocommunity structure over the last 3.6 million years: A southern California case study
We culled abundance record data from the NSF-funded TCN, Eastern Pacific Invertebrate Communities of the Cenozoic (EPICC), including all southern California localities that recorded the presence of oysters from the last 3.6 million years to document how oyster communities change through time. In total, over 120,000 specimens from 78 localities throughout southern California (i.e., Los Angeles, Orange, and San Diego counties) were examined. The data were broken down into four-time bins: late Pliocene, middle Pleistocene, late Pleistocene, and Holocene. Using multivariate statistics, several statistically coherent groups based on occurrences and abundances through time were indentified. Results indicate that the late Pliocene coherent groups possessed a loose, facultative, individualistic community structure that allowed taxa to shift their latitudinal gradients as they tracked shifting environments. The dominant oyster—Dendrostrea vespertina—as well as other taxa, became extinct at the Plio-Pleistocene boundary. Afterwards, community structure changed, as did the dominant oyster. We suspect that the onset of northern hemisphere glaciation at the Plio-Pleistocene boundary changed both the magnitude and rate of sea surface temperatures such that local extinction occurred causing changes in dominance within marine communities. During the middle Pleistocene, Ostrea conchaphila (lurida) appeared and remained dominant throughout the Holocene. In addition, distinct spatial groups existed causing reduced migration along the coast of southern California. Perhaps southern California marine communities responded to the water-mass differences associated with the mid-Pleistocene transition from a mild, 41 ka glacial-interglacial cycle to the more variable ~100 ka glacial-interglacial cycle reducing migration along the coast of southern California. The loose, individualistic community structure seen in the late Pliocene returned during the late Pleistocene and continued through the Holocene allowing marine communities the flexibility to track shifting environments.