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Research : PaleoBios
Abstracts (vols. 21 to 25)
PaleoBios 21(1), April 30, 2001
Barstovian (Miocene) beavers from Stewart Valley, Nevada, and a discussion of the genus Monosaulax based on tooth morphology
The morphometric variability of beavers from the Stewart Valley, Nevada, is detailed. The best represented Barstovian sites from the Stewart Valley, Tedford Pocket, and Stewart Springs produced ample material of Monosaulax and a single tooth of Anchitheriomys, which form the basis for this report. Most teeth belong to M. pansus and show morphological and metric variability comparable to other beaver populations. A proximal skull fragment of Monosaulax, assigned to M. pansus, is described. Metric analysis of the cheek teeth differentiated according to wear stages indicates the possible presence of three size groups of Monosaulax and the teeth are tentatively assigned to M. curtis, M. pansus and a larger Monosaulax sp. However, difficulties with the differentiation of beaver species based only on size as generally done are discussed.
New cycadophytes from the Upper Triassic Chinle Formation of the southwestern United States
The Upper Triassic formations in the southwestern United States contain a large number of cycadophyte fossils representing a variety of species. In this report two new species of cycadalean leaves, Pseudoctenis stewartii and Nilssonia lewisii, and a new species of bennettitalean leaves, Zamites tidwellii are described from the Upper Triassic Chinle Formation in Utah and New Mexico. These fossils bring the total number of cycadophytes based on megafossils found in the Chinle Formation to 12, including five cycads and seven bennettitaleans. The occurrence of such a variety and number of cycadophytes in the Chinle Formation indicates that these plants were an important component of the Upper Triassic flora of the southwestern United States. They also demonstrate that many of the key vegetative and at least some reproductive characters of the cycadophytes were established by this time.
PaleoBios 21(2), September 15, 2001
Reassessing the Lambdotherium first appearance datum (Wasatchian, early Eocene) in the Bighorn Basin, Wyoming
KRISTER T. SMITH
The Lambdotherium first appearance datum (FAD) is an important biostratigraphic indicator in the early Eocene of the Rocky Mountain Interior, defining the base of the Lostcabinian provincial land-mammal "subage." Previous studies have placed this datum at different levels in the Elk Creek section of the central Bighorn Basin; as currently documented, the correct level is 591 m. However, a survey of the Yale Peabody Museum collections revealed that four specimens of Lambdotherium derive from localities below the previously documented FAD. One of these is from a locality correlated to 501 m in the Elk Creek composite section, 90 m below the previous FAD; another specimen is from the 511-m level, and two others are from the 561-m level. Magnetostratigraphic correlation with the McCullough Peaks section to the north suggests that the Lambdotherium FAD may be diachronous by as much as 200 kyr. Alternatively, the FAD may actually be lower than currently documented in the McCullough Peaks area; increased sampling intensity may help to resolve this issue. Even if the Lambdotherium FAD is diachronous, that taxon would remain a strong temporal indicator. However, its usefulness for defining chronostratigraphic and therefore geochronologic units (e.g., Lostcabinian) would be compromised.
Non-articular periostosis of a proximal phalanx of Equus conversidens
ERIC SCOTT1 and JAMES R. ROONEY2
Non-articular periostosis involving the distal end of a proximal phalanx of Equus conversidens is described. While not uncommon in fossil and recent equids, this is the first report of this paleopathology in E. conversidens. Based on remnants of epiphyseal plates, the animal was between one and two years of age at time of death.
Mega-invertebrate fossils from Tertiary rocks of the Spreckles 7.5' quadrangle, Monterey County, California, with description of an unusual faunule from the Monterey Formation and a new lucinid bivalve from the Santa Margarita Sandstone
CHARLES L. POWELL, II
A paleontologic review of mega-invertebrate fossil collections from the Spreckles 7.5' quadrangle to accompany new geologic mapping of the quadrangle is presented. Fossils are recorded from three stratigraphic units in the quadrangle: (1) unnamed sandstone of Clark and others (2000); (2) the Monterey Formation; and (3) the Santa Margarita Sandstone. The unnamed sandstone contains a small molluscan assemblage of 10 taxa that suggests a "Temblor" provincial molluscan age (middle Miocene) and shallow shelfal marine conditions. The Monterey Formation contains two distinct faunas, one from the diatomaceous facies and another from the more arenaceous rocks. The fauna from the diatomaceous rocks contains questionably deep-water taxa (mollusks and brachiopods). These taxa are assumed to be deep-water because of the sediments in which they are collected reflect deep water and they are thin shelled. The fauna from the arenaceous part of the Monterey Formation suggests shallower water depths. The occurrence of Pacipecten discus (Conrad) in both the Monterey and Santa Margarita Sandstone suggests a "Margaritan" provincial molluscan age (late Miocene) for these formations, although superposition shows that the Monterey Formation is older than the Santa Margarita Sandstone. The Santa Margarita Sandstone contains a small fauna of 38 mollusks, one arthropod, and one echinoderm in the Spreckles quadrangle. These taxa suggest normal marine conditions at shelfal water depths. A new lucinid bivalve, Lucinisca? brabbi n. sp., is also described from the Santa Margarita Sandstone.
PaleoBios 21(3), December 21, 2001
Terrestrial plant fossils from the Mississippian Diamond Peak Formation,
CHRISTOPHER G. MATTINSON and
BRUCE H. TIFFNEY
Land plant remains are preserved in shallow water turbidite deposits within the upper Mississippian Diamond Peak Formation in the northern White Pine Range, White Pine County, Nevada. These deposits represent debris shed eastward from the Antler Mountains into the Antler Basin. Poor preservation limits the precision of identification, but six forms can be recognized including Lepidodendron cf. aculeatum and Lycopodites sp., Archaeocalamites radiatus, A. species, and Sphenophyllum?. An axis with a spiral branching pattern may represent a seed plant. Several specimens exhibit a consistent morphology of whorls or bracts with a cruciate cross section; these may be reproductive organs. This assemblage indicates that a Euramerican-type swamp flora existed on the eastern flank of the Mississippian Antler Mountains, typical of low-latitude tropical floras of the Carboniferous.
Evidence of pathology in early Cenozoic turtles
J. HOWARD HUTCHISON1 and FREDRIC L. FRYE2
Survey of fossil turtle shells and fragments from selected Eocene localities of Wyoming yielded numerous examples of non-developmental pathologic injury. A few of these are clearly the result of predator damage indicated by bite holes and gouge marks. A brief review of the causes of the other injuries, particularly sublaminal pitting of the shell, implicates possible sources from fungal, algal, bryozoan, and bacterial infections, but these remain inconclusive on a case by case basis, pending more detailed study, description, and causes of similar injuries in extant turtles. Comparisons of the relative frequency of pathologies in different turtle paleopopulations suggest that environmental conditions may play a role in the etiology of these pathologies.
PaleoBios 22(1), May 15, 2002
Description of Montanazhdarcho minor, an azhdarchid pterosaur from the Two Medicine Formation (Campanian) of Montana
MICHAEL R. McGOWEN1, KEVIN PADIAN1,2, MICHAEL A. DE SOSA1, and ROBERT J. HARMON2 1Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California 94720. 2Museum of the Rockies, Montana State University, Bozeman, MT 59717
The wing skeleton of the Campanian azhdarchid pterosaur Montanazhdarcho minor Padian et al. 1995 is described and compared to other Cretaceous pterosaurs. It is distinguished from all other known azhdarchids by its small mature size, among other characters. Notable features include elongated cervical vertebrae with weak neural crests, a ring-like pectoral girdle, and an unwarped deltopectoral crest that is 30% of the length of the humerus. The ulna is slightly longer than the wing metacarpal, and the articular surface of the radius lacks a central pneumatic foramen. The wing metacarpal has a rounded dorsal condyle but there is no median ridge between the distal condyles. The mandible is edentulous. Further support is given to the reduced distal expansion of the deltopectoral crest as an azhdarchid synapomorphy.
A new species of Plesiocathartes (Aves: ?Leptosomidae) from the Middle Eocene of Messel, Germany
A new species of the genus Plesiocathartes Gaillard 1908 is described from the middle Eocene of Messel (Germany). Plesiocathartes kelleri sp. nov. is represented by two articulated skeletons and is the most substantial record of the genus, previously only known from a few isolated bones. In addition, a distal end of a tarsometatarsus of Plesiocathartes sp. is described from the lower Eocene London Clay of England. The new specimens clearly demonstrate that Plesiocathartes is no early European representative of the Cathartidae (New World vultures) as assumed by earlier authors. Instead, both in terms of derived characters and in overall morphology, Plesiocathartes kelleri most closely corresponds to the Leptosomidae (Cuckoo-rollers), which today only occur in the Madagascan region. Accordingly, the genus Plesiocathartes is tentatively assigned to the Leptosomidae. If this classification is correct, it would be the first Tertiary fossil record of the Leptosomidae, and indicate that the extant distribution of this family is relictual.
PaleoBios 22(2), October 31, 2002
Dental variation and temporal change in
FRANK P. CUOZZO
This study investigates patterns of dental variation and temporal change in a sample of 627 stratigraphically controlled Hyopsodus specimens from the early Eocene of the Powder River Basin, Wyoming. Specimens studied span a stratigraphic interval of 140 meters of section, and represent a biostratigraphic range form the later Wa2 to early Wa3 faunal zones of the Wasatchian North American Land Mammal Age. Among the patterns observed is a distinct size increase early in Wa3, the uppermost of the six stratigraphic levels sampled, illustrated by the largest mean for 11 of the 16 variabless studied occurring at this top level. In addition, all variables (other than those which have several single specimen startigraphic level samples) show a size increase between the latest Wa2 level and early Wa3. This pattern of increasing size early in Wa3 is seen in other mammals (e.g., Haplomylus and Apheliscus) in the Powder River Basin (Robinson 1986), and in Hyopsodus in other intermontane basins of North America, such as the Clark's Fork Basin (Gingerich 1994). This size increase corresponds to the general (relative) cooling trend that occurred during the transition from the early to middle Wasatchian in North America documented in the Bighorn Basin (e.g., Bown et al. 1994, Wing 1998, Wing et al. 2000). Although not focused on taxonomy, a cursory morphological analysis suggests the presence of two distinct Hyopsodus lineages throughout the stratigraphic interval sampled, as does the amount of metric variation seen for a number of tooth positions at different stratigraphic levels (CV > 10 in 19 of 86 total measurements). THe indication of two distinct Hyopsodus lineages provides support for an earlier report for the Powder River Basin (Robinson 1986), and corresponds to the general pattern of Hyopsodus diversity seen throughout western North America during the early Eocene (e.g., Redline 1997).
New evidence of large dicynodonts in the upper Moenkopi Formation (Middle Triassic) of northern Arizona
STERLING J. NESBITT1 and
KENNETH D. ANGIELCZYK1,2
Large dicynodont tracks and bones have been disocvered in the Perovkan age (= Early Anisian) upper Moenkopi Formation of northern Arizona, representing the earliest appearance of this group in North America. Dicynodont fossils are found throughout the stratigraphic section of the Holbrook Member and include a worn tusk, a cervical vertebra, two isolated footprints, and a trackway. The tusk was discovered in the uppermost sandsone of the Holbrook Member, making it the highest known occurrence of a vertebrate in the Moenkopi Formation sequence. The cervical vertebra was discovered in a conglomerate channel midway through the stratigraphic sequence of the Holbrook Member. The trackway was published as the holotype of the ichnospecies Therapsipus cumminsi, and the isolated footprints also can be referred to this taxon. One of the isolated footprints was found at nearly the same stratigraphic level as the vertebra, wheras the other was discovered in the lowermost sandstone of the Holbrook Member and represents the lowest occurrence of dicynodonts in the formation.
PaleoBios 22(3), December 15, 2002
Osteological correlates of cervical musculature in Aves and Sauropoda (Dinosauria: Saurischia), with comments on the cervical ribs of Apatosaurus
MATHEW J. WEDEL1 and
R. KENT SANDERS2
The cervical muscles of birds attach to specific bony features on the vertebrae. Most of these osteological correlates are also present in the cervical vertebrae of sauropod dinosaurs, which suggests similar cervical musculature in the two groups. One exception is the processus caroticus, which anchors the long ventral muscles of the bird neck but has no obvious homolog in the vertebrae of sauropods.
Comments on the generic synonymy of Anemorhysis Gazin 1958 and Tetonoides Gazin 1962 (Mammalia, Primates), with a description of new early Eocene omomyid specimens from the Washakie Basin, Wyoming
FRANK P. CUOZZO
The current study presents a description of new small-bodied omomyid specimens from the early Eocene of the Washakie Basin, Wyoming, discussed here as a part of a broader study of the Eocene primates Tetonoides pearcei and Anemorhysis savagei. Specimens studied date to the Late Graybullian and Lysitean faunal zones of the Wasatchian North American Land Mammal Age, and represent previously described and recently recovered specimens. Among the new materials are several multi-toothed jaw specimens from the Bitter Creek area of the Washakie Basin. Metric and morphologic data for the overall sample, including these new specimens, were analyzed for each individual species, and as a combined data set. Despite being from two distinct faunal zones (Late Graybullian and Lysitean for T. pearcei and A. savagei respectively), the amount of metric variation for the combined sample, seen for example in the lengths of M1 (CV=2.8, n=26) and M2 (CV=3.5, n=25), is consistent with the amount of variation seen in single-species samples of extant small-bodied primates and is less than that exhibited in many small-bodied primate generic samples, both extant and extinct. Despite some subtle differences, there is a consistent overall morphologic pattern seen throughout the combined sample, which is not unexpected, as these two forms exhibit similar adaptive profiles. Therefore, the data presented here suggest that, in contrast to a number of previous reports, a generic distinction between T. pearcei and A. savagei is not supported. Rather, Tetonoides is viewed here as a junior synonym of Anemorhysis, in agreement with Bown and Rose (1984, 1987), and Gunnell and Rose (2002), following Szalay (1976, 1982).
PaleoBios 23(1), April 15, 2003
Functional diversity within the Littleton fauna (early Paleocene), Colorado: evidence from body mass, tooth structure, and tooth wear
ERIC W. DEWAR
In this study, ecomorphological techniques, based primarily on the implications of body size and mastication, are used to model dental functional diversity of an earliest Tertiary paleocommunity. The Littleton fauna is a diverse assemblage of mammals from early Paleocene strata of the Denver Formation of Colorado. This fauna falls within Interval-zone Pu1, between the Mantua Lentil local fauna and the type Puercan localities of the San Juan Basin. The assemblage is composed of multituberculates, "proteutheres," archaic ungulates ("condylarths"), and one marsupial species, along with a less diverse lower vertebrate component. Inferences of dental function were made by combining measurements of tooth morphology and gross wear facets with estimates of body masses. These dental measurements are evaluated in terms of which mode of food fracture they would optimize. Two overall food type groups can be discerned by these criteria. A "soft tough" food group is identified by species with typically more gracile and sectorial teeth with variable degrees of abrasive wear, including Peradectes pusillus, Oxyclaenus n. sp., Conacodon harbourae, and Baioconodon n. sp. The medium-sized species Alticonus gazini and Baioconodon denverensis are grouped into a "hard brittle" food group. They differ noticeably from the other medium-sized species in morphology, particularly in their lower trigonid-talonid relief, more rounded crest outlines, and similarity in degree of Phase I to Phase II wear and dentine exposure. Although it was expected that a mammalian assemblage present so soon after the Cretaceous-Tertiary transition would have been filled with insectivores or generalists, similar to the trophic patterns known from the Late Cretaceous, the taxa resident in this fauna were unexpectedly diverse in dental function.
The first Mesozoic mammal from California
GREGORY P. WILSON1,
RICHARD P. HILTON2, and ERIC S. GÖHRE3
A new specimen from the Upper Cretaceous (Campanian) marine deposits of the Chico Formation represents the first Mesozoic mammal from California. The specimen adds to the fauna, which includes dinosaurs, turtles, pterosaurs, and birds, known from this nearshore terrestrial environment. The specimen, a metacarpal, cannot be confidently identified beyond the level of Mammalia. However, the size of the specimen suggests that the animal was a medium to large-sized Mesozoic mammal, larger than the Late Cretaceous eutherian Barunlestes butleri and comparable to the modern day Eurasian hedgehog (Erinaceus europaeus).
The oldest turtle from California and other new records of Late Cretaceous sea turtles from the Chico Formation
JAMES FORD PARHAM1,
RICHARD P. HILTON2, and ERIC S. GÖHRE3
New turtle specimens from the Upper Cretaceous Chico Formation of California are described. This material includes the left humerus of a juvenile turtle (VRT 46) that can be referred to the Protostegidae. In addition to being an important addition to the Chico Formation sea turtle fauna, VRT 46 is also the oldest turtle from California. The Late Cretaceous turtle fauna of the Pacific was more diverse than previously known as it now includes representatives of all three major chelonioid clades: Cheloniidae, Dermochelyidae, and Protostegidae.
PaleoBios 23(2), September 15, 2003
The pelvic and hind limb anatomy of the stem-sauropodomorph Saturnalia tupiniquim (Late Triassic, Brazil)
MAX CARDOSO LANGER
Three partial skeletons allow a nearly complete description of the sacrum, pelvic girdle, and hind limb of the stem sauropodomorphSaturnalia tupiniquim, from the Late Triassic Santa Maria Formation, South Brazil. The new morphological data gathered from these specimens considerably improves our knowledge of the anatomy of basal dinosaurs, providing the basis for a reassessment of various morphological transformations that occurred in the early evolution of these reptiles. These include an increase in the number of sacral vertebrae, the development of a brevis fossa, the perforation of the acetabulum, the inturning of the femoral head, as well as various modifications in the insertion of the iliofemoral musculature and the tibio-tarsal articulation. In addition, the reconstruction of the pelvic musculature of Saturnalia, along with a study of its locomotion pattern, indicates that the hind limb of early dinosaurs did not perform only a fore-and-aft stiff rotation in the parasagittal plane, but that lateral and medial movements of the leg were also present and important.
ERRATUM to Wedel and Sanders. 2002. PaleoBios 22(3):1-6.
MATHEW J. WEDEL1and
R. KENT SANDERS2
Since the publication of Wedel and Sanders (2002), two errors in the text have come to our attention. The first concerns the presence or absence of the process ventralis corporis in sauropods, and the second concerns Gilmore's (1936) statements regarding the cervical ribs of Apatosaurus.
PaleoBios 23(3), December 15, 2003
Issue in Honor of the Contributions to Paleontology made by J. Howard Hutchison
A new Late Jurassic turtle specimen and the taxonomy of Palaeomedusa testa and and Eurysternum wagleri
WALTER G. JOYCE
A new fossil turtle specimen from the Late Jurassic of Solnhofen, Germany, provides new insights into the validity of the species Palaeomedusa testa. The new specimen exhibits a number of characters in the carapace, such as the absence of well-developed fontanelles and the presence of three cervicals, five pleurals, and narrow vertebrals, which are present in Palaeomedusa testa, but not in Eurysternum wagleri. These characters warrant the tentative placement of the new turtle in Palaeomedusa testa and the refutation of the traditionally accepted synonymy between Eurysternum wagleri and Palaeomedusa testa. An additional taxon, Thalassemys marina, is also cautiously placed in Palaeomedusa testa, thus synonymizing Thalassemys marina with Palaeomedusa testa. The presence of three cervicals and a wide, trapezoidal nuchal is currently thought to be diagnostic of the Plesiochelyidae and Eurysternidae, respectively, but both characters occur simultaneously in Palaeomedusa testa. Consequently, one of these characters must have been lost during phylogeny or evolved twice and therefore is not useful in diagnosing a monophyletic group of turtles. Finally, the fossil taxon Eurysternum wagleri, which is primarily diagnosed by its deep pygal notch, is based on the description of an illustration of an incomplete and now missing fossil turtle specimen. Although the designation of a neotype may be useful, this study demonstrates that no eligible specimen is available, and as such, the type illustration will have to suffice until a neotype is found.
Gravemys Sukhanov and Narmandakh, 1983 (Testudinoidea: Lindholmemydidae) from the Late Cretaceous of Asia: new data
The study of new specimens of Gravemys barsboldi, a rare lindholmemydid turtle from the Late Cretaceous of Mongolia,reveals new details regarding its morphology. These include a clear overlapping of marginal 12 onto suprapygal 2, inguinal buttress reaching the two thirds of the width of costal 5 and contacting the costals 5-6 suture laterally, variably shaped inframarginals and viability (straight or sinuous) medial pectoral sulcus. Gravemys hutchisoni, sp. n., is based on the paratype specimen of Mongolemys trufanensis Yeh, 1974, from the Late Cretaceous of Turfan (Xinjiang, China). This new assignment is based on the similarity in shape of the plastral lobes, the presence of four pairs of inframarginals that strongly onlap the peripherals, and a shortened entoplastron.
The first report of hard-shelled sea turtles (Cheloniidae sensu lato) from the Miocene of California, including a new species (Euclastes hutchisoni) with unusually plesiomorphic characters
SHANNON COLLEEN LYNCH1 and
JAMES FORD PARHAM2
In this paper we describe the first cheloniid turtle fossils from the Miocene (Barstovian) of California, USA. All specimens are from Sharktooth Hill, Round Mountain Silt Member of the marine Temblor Formation, in Kern County. The material includes two species: (1) a form with a sculptured carapace (cf. Syllomus) known from a single specimen; (2) a form with unusually plesiomorphic characters including a wide plastron, a Toxochelys-like humerus, femoral trochanters separated by a deep fossa, a broad sutural contact between the vomer and premaxillae on the palatal surface, and a single facet on the anterior end of the eighth cervical vertebra. This second sea turtle can be differentiated from other cheloniid taxa and so is named a new species, Euclastes hutchisoni. A cladistic analysis of 13 cheloniid taxa and 34 morphological characters suggests a phylogenetic position of Euclastes hutchisoni far-removed from the living cheloniids. Euclastes hutchisoni appears to be the last member of a Cretaceous-Paleocene radiation of durophagous stem cheloniids.
PaleoBios 24(1), May 15, 2004
First record of a turtle (Protochelydra, Chelydridae, Testudines) from the Cenozoic of Alaska (Chickaloon Formation, Paleocene-Eocene)
J. HOWARD HUTCHISON1 and ANNE D. PASCH2
A chelydrid turtle from the late Paleocene (Clarkforkian NALMA) of the Chickaloon Formation, near Anchorage, is the first record of a turtle from the Cenozoic of Alaska and the most northerly record of the family known thus far. The specimen consists of a partial carapace from a plant-rich carbonaceous mudstone. It compares most closely with Protochelydra zangerli from the late Paleocene (Tiffanian NALMA) of North Dakota.
Postcranial material of Jachaleria candelariensis Araújo and Gonzaga 1980 (Therapsida, Dicynodontia), Upper Triassic of Rio Grande do Sul, Brazil
Additional postcranial material attributed to the Late Triassic dicynodont Jachaleria candelariensis Araújo and Gonzaga, found in Rio Grande do Sul State, Brazil, is described. All material came from the same outcrop and stratigraphic level as the holotype, and consists of disarticulated and sometimes fragmentary bone elements. The preserved axial skeleton consists of eight cervical, five middle dorsal, two posterior dorsal and two caudal vertebrae, two cervical ribs, six anterior dorsal ribs, thirteen posterior dorsal ribs and a sternum. We also identified three scapulae, two ulnae, five radii, two pelvic girdles, two ilia, two femora, a tibia and a calcaneum. Based on the studied material, a reconstruction of the specimen is presented. The lack of a complete scapular girdle and a humerus makes the posture of the forelimbs uncertain, but the morphology of the femur and pelvic girdle indicates that the hind limbs of Jachaleria should be should be upright, as in the other Triassic dicynodonts.
PaleoBios 24(2), September 15, 2004
Early Eocene Microsyops (Mammalia, ?Primates) from the Washakie Basin, southern Wyoming, with a description of newly recovered specimens
FRANK P. CUOZZO1 and
KELLY T. INMAN2
Microsyops is a small-bodied mammalian genus that spans a biostratigraphic range from the early through late middle Eocene of North America, and is well-known from many areas of the interior Rocky Mountain region. Microsyops has previously been described in detail, largely based on material from the better-known early Tertiary basins of Wyoming (e.g., Bighorn and Wind River Basins). Here we present data on a stratigraphically controlled Microsyops sample from the early Eocene (Graybullian and Lysitean faunal zones) of the Washakie Basin, Wyoming. Although the sample described here consists primarily of isolated teeth, one specimen collected in 2001 from Lysitean strata (biochron Wa6) in the Bitter Creek area of the basin preserves the mandibular symphysis, alveoli for the incisor and P2, and complete teeth from P3 through M2. Measurements for this specimen fall within published size ranges for M. latidens. In addition, this specimen exhibits a P4 talonid morphology (distinct hypoconulid) consistent with that of M. latidens. Specimens from the older Graybullian strata of the Bitter Creek and Patrick Draw areas exhibit a morphology consistent with M. angustidens (e.g., variably present maxillary molar mesostyles). The apparent transition from M. angustidens to M. latidens across the Graybullian-Lysitean boundary in the Washakie Basin is consistent with the pattern of phyletic change seen in Microsyops in other areas of Wyoming (e.g., Bighorn Basin). This suggests a general pattern of early Tertiary biostratigraphic change and taxonomic diversity for microsyopids throughout the northern Rocky Mountain region.
New skull material of Osteodontornis orri (Aves: Pelagornithidae) from the Miocene of California
THOMAS A. STIDHAM
New material of the bony-toothed bird Osteodontornis orri from the middle Miocene Round Mountain Silt on Sharktooth Hill, Kern County, California clarifies the identification of some Asian Osteodontornis material and provides previously unreported morphological details of the rostrum of Osteodontornis and pelagornithids. This material is approximately the same age as the O. orri holotype and some of the referred Osteodontornis material from California, and is younger than the Osteodontornis material from Japan. The Sharktooth Hill specimens have some morphological characters in common with specimens from Japan (e.g., neurovascular groove on the medial surface of the dentary), and the new specimens differ somewhat morphometrically from the older and penecontemporaneous material. The new material supports the assignation of the Japanese material to O. orri, and suggests that O. orri either had greater variation in size among individuals than currently is recognized or possibly underwent size change over its geologic history.
First occurrence of Brachiosaurus (Dinosauria: Sauropoda) from the Upper Jurassic Morrison Formation of Oklahoma
MATTHEW F. BONNAN1 and
MATHEW J. WEDEL2
The giant sauropod Brachiosaurus is one of the rarest sauropods from the Upper Jurassic of North America. The genus has previously been reported from Colorado, Utah, and Wyoming. OMNH 01138 is a sauropod metacarpal of unusual proportions from the Upper Jurassic Morrison Formation of Oklahoma. The bone is longer and more slender than the metacarpals of diplodocids and Camarasaurus, and is most similar in size and proportions to the elongate metacarpals of Brachiosaurus. This is the first report of Brachiosaurus from Oklahoma.
PaleoBios 24(3), December 22, 2004
The first discovery of a rhynchosaur from the upper Moenkopi Formation (Middle Triassic) of northern Arizona
STERLING J. NESBITT1 and
ROBIN L. WHATLEY2
Ammorhynchus navajoi gen. et sp. nov. (Archosauromorpha: Rhynchosauria) is described from a nearly complete left maxilla and additional dental elements from lower Middle Triassic (Lower Anisian) deposits of the Moenkopi Formation of Arizona. The single maxillary groove present in Ammorhynchus navajoi gen. et sp. nov. occurs in some species of the Middle Triassic genus Rhynchosaurus, but is consistently present in Late Triassic forms of the genus Hyperodapedon, and is typical of all other North American rhynchosaurs. The presence of the single maxillary groove, in combination with well-developed maxillary lingual teeth and a low occlusal tooth row count, suggests that this is the plesiomorphic condition in all rhynchosaurs with blade and groove occlusion. Ammorhynchus navajoi gen. gen. et sp. nov. is the first rhynchosaur reported from the Moenkopi Formation (Holbrook Member), and is the earliest rhynchosaur known from the Americas.
First report of Megapnosaurus (Theropoda: Coelophysoidea) from China
RANDALL B. IRMIS
The biota of the Lower Jurassic Lufeng Formation (Yunnan Province, China) is critical to understanding Early Jurassic tetrapod evolution and biogeography. Theropod dinosaur material from the Lufeng Formation remains enigmatic and poorly known. For this reason, any theropod material that can be unequivocally identified as a particular taxon is valuable in understanding the theropod fauna of the Lufeng Formation. Here, two specimens are reported as being the first record of the dinosaur Megapnosaurus from the Lufeng Formation, and the whole of Asia. The presence of Megapnosaurus is consistent with previous work suggesting an Early Jurassic age for the Lufeng Formation. It also greatly extends the geographic range of the genus, and confirms the pangeographic distribution of Early Jurassic terrestrial tetrapods.
Mammuthus jeffersonii (Proboscidea, Mammalia) from Northern Illinois
MICHAEL R. PASENKO1 and BLAINE W. SCHUBERT2
A lower second molar of a Jeffersonian mammoth (Mammuthus jeffersonii) from northern Illinois provides the first reliable record of this species from the state. A radiocarbon date of 11,170 ± 140 14C yr B.P. on spruce (Picea) wood from the site suggests an age of late Pleistocene for the mammoth specimen. Although this is the first description of M. jeffersonii from Illinois, the locality is within the expected range of this taxon. The restricted geographical distribution of M. jeffersonii in the upper Midwest during the late Pleistocene may indicate a close association between this species and spruce-dominated open forests.
PaleoBios 25(1), April 15, 2005
Conical fossils from the Lower Cambrian of Eastern California
Two new cone-shaped fossils from Lower Cambrian strata of eastern California are described and compared to hyolithids from the region. Lathamoserpens sigel n. gen., n. sp. occurs in both the Latham Shale in the Mojave Desert and the Poleta Formation of the White-Inyo region. Lathamoserpens is a large tubular fossil characterized by a central keel and a sigmoid shape. Although it resembles hyolithids, its taxonomic affinity is uncertain. The thin-walled conical fossil Cambrorhytium fragilis, first described from the Burgess Shale, also occurs in the Latham Shale; C. fragilis has been proposed to be a cnidarian polyp tube but lacks diagnostic features that allow this hypothesis to be tested. Both of these fossils are distinct from known hyoliths from the Latham Shale, which are tentatively assigned to Nevadotheca whitei.
"Old World phorusrhacids" (Aves, Phorusrhacidae): a new look at Strigogyps ("Aenigmavis") sapea (Peters 1987)
The discovery of phorusrhacid-like birds (Aves, Phorusrhacidae) in early Tertiary deposits of France and Germany has been of great paleobiogeographic interest, as these flightless birds were previously known only from the New World. In this study, the species from Messel in Germany ("Aenigmavis") sapea (Peters 1987) is reevaluated and its taxonomy revised. It is shown that Aenigmavis Peters 1987 and Ameghinornis Mourer-Chauviré 1981, the other European taxon, are junior synonyms of Strigogyps Gaillard 1908. Strigogyps ("Ameghinornis") minor Gaillard 1939 is considered a junior synonym of Strigogyps dubius Gaillard 1908. A newly identified, well-preserved wing of Strigogyps is described and it is shown that this taxon lacks several derived characters that characterize the Phorusrhacidae, including a dorso-ventrally deep mandible, a strut-like coracoid, an extremely reduced wing, a block-like hypotarsus, and a reduced hindtoe.
A new Upper Triassic flora and associated invertebrate fossils from the basal beds of the Chinle Formation, near Cameron, Arizona
A small but varied fossil biota consisting mostly of plant remains occurs in the Chinle Formation of Late Triassic age near the village of Cameron in north-central Arizona. The biota is significant because it occurs near the base of the formation in the Shinarump Member and contains several plant taxa and invertebrate fossils not previously reported from the Chinle Formation as well as a few species typically found elsewhere in the lower part of the Chinle Formation. The horsetails are represented by Equisetites bradyi Daugherty (1941) and the ferns and fern-like foliage by Phlebopteris smithii (Daugherty) Arnold (1947), Cameronopteris breedii gen. et sp. nov., and Cladophlebis brownii sp. nov. The gymnosperms include the cycads Palaeocycas wardii sp. nov. and Macrotaeniopteris kokopellia sp. nov., the bennettites Zamites powellii Fontaine (in Fontaine and Knowlton 1890) and Eoginkgoites davidsonii Ash (1977), the leafy shoot of the conifer Pagiophyllum sp., and a single seed-bearing structure of the Dinophyton spinosus Ash (1970c) plant. The invertebrate fossils associated with the Cameron flora include poorly preserved shells of the polychaete worm Spirorbis sp., two types of insect eggs, and an oval feeding trace on the leaf M. kokopellia. The first type of insect egg is round and occurs in an unattached mass. The second type is elliptical in outline and is exposed on the surface of the compressed stems of a large horsetail. They are similar to eggs oviposited in the stems and leaves of plants by certain living Odonata (dragonflies and damselflies). The feeding trace is similar to some of those found on other leaves in the Chinle Formation and tentatively attributed to the activities of beetles.
PaleoBios 25(2), September 26, 2005
The phylogenetic taxonomy of Diplodocoidea (Dinosauria: Sauropoda)
Despite some continuing controversies, sauropod phylogeny is now the subject of broad agreement. Against this backdrop of relatively stable phylogenetic hypotheses, however, the nomenclature of the sauropod clade that includes Diplodocus and its relatives remains confused. Not all of the named groups within this clade have suitable phylogenetic definitions; others have multiple names; and some names have multiple conflicting definitions. We survey the taxonomic history of this clade, consider the suitability for phylogenetic taxonomy of various candidate definitions from the literature, and discuss some sources of confusion. Finally, we recommend "best practice" in the use of the relevant clade names.
Cenomanian (Late Cretaceous) reptiles from northwestern Russell County, Kansas
GREGORY A. LIGGETT1, 5, KENSHU SHIMADA2, 5, S. CHRISTOPHER BENNETT3, 5, and BRUCE A. SCHUMACHER4, 5
Several Late Cretaceous reptilian fossils were found at and immediately above the contact between the Graneros Shale and the Lincoln Limestone Member of the Greenhorn Limestone in northwestern Russell County, Kansas. The taxa recovered include: (1) an indeterminate plesiosaur taxon; (2) the rare pliosaurid plesiosaur Brachauchenius lucasi; (3) a pteranodontoid pterosaur, which constitutes the earliest occurrence of a flying reptile in Kansas; and (4) the rare aquatic lizard Coniasaurus. Several morphologic characters of B. lucasi are clarified: an apomorphy in the paddle of B. lucasi where both the fourth and fi fth metapodials intrude on the mesopodial row is noted for the first time; and striations of tooth enamel vary from the tooth crown to the root and from the front to the back of the tooth. Additionally, the stratigraphic occurrence of B. lucasi suggests that the minimal stratigraphic range for that species is from the late Cenomanian through middle Turonian. This diverse reptile fauna occurs with a variety of fossil fishes consisting of at least twelve chondrichthyan and four osteichthyan taxa. The age of the fauna is middle Cenomanian based upon the site’s stratigraphic occurrence and a radiometric date of 95.53 ± 0.159 Ma obtained one meter below the excavation. Whereas reptilian faunas of this age from the eastern margin of the Cretaceous Interior Seaway are relatively rare, this faunal assemblage adds significant paleoecological information about Western Interior Basin biogeography.
New camels (Mammalia: Artiodactyla) from the Barstow Formation (middle Miocene), San Bernardino County, California
The Barstow Formation (He2-Ba2) exhibits high levels of camelid diversity, with fi ve genera and six species, including Miolabis fissidens, Protolabis barstowensis, Paramiolabis singularis, and Aepycamelus alexandrae. Two new camels from the Barstow Formation are described, Paramiolabis minutus Barghoorn, 1985, and Michenia mudhillsensis new species.
PaleoBios 25(3), December 23, 2005
Phylogenetic taxonomy and the names of the major archosaurian (Reptilia) clades
Much disagreement exists as to what names to apply to the major clades of the reptilian taxon Archosauria. Even among practitioners of phylogenetic taxonomy, there has been a tendency to apply the principles of phylogenetic taxonomy to the naming of some archosaurian clades while resisting the principles of phylogenetic taxonomy for other clades. Here, the principles of phylogenetic taxonomy are applied to the major clades of Archosauria, and the correct names for these clades within the paradigm of phylogenetic taxonomy are delineated. Within this paradigm, the names of the major archosaurian clades are as follows. Archosauria: the most exclusive clade containing Crocodylia and Aves. Archosauriformes: the most exclusive clade containing Proterosuchus and Archosauria. Pseudosuchia: the most inclusive clade within Archosauria that includes Crocodylia but not Aves. Crurotarsi: the most exclusive clade containing Parasuchia, Ornithosuchidae, Prestosuchus, and Suchia. Ornithosuchia: the most inclusive clade within Archosauria that includes Aves but not Crocodylia. Ornithodira: the most exclusive clade containing Pterosauria, Scleromochlus and Dinosauromorpha. Avialae: the most inclusive clade containing ornithuran birds but not deinonychosaurian theropods. Aves: the most exclusive clade containing Archaeopteryx and extant birds. Neornithes: the most exclusive and extant birds.
Functional analysis of the hands of the theropod dinosaur Chirostenotes pergracilis: evidence for an unusual paleoecological role
PHIL SENTER1 and
J. MICHAEL PARRISH2
We report the first functional study of the forelimbs of an oviraptorosaurian dinosaur. The diet of these typically toothless dinosaurs has long been a mystery. The hands of the Late Cretaceous North American oviraptorosaur Chirostenotes pergracilis exhibit a greatly elongated second digit with an unusually straight ungual, the functional significance of which has not previously been explored. Direct manipulation of the manual skeleton of C. pergracilis and comparison with other theropods reveals that the range of motion in its hands is not greatly modified from the plesiomorphic maniraptoran condition. From this we infer that the significance of the modified second finger of Chirostenotes is unrelated to functions that would have required a change in manual range of motion and is instead related to some function requiring one finger to be much longer than the others. Comparison with the anatomical requirements for a variety of manual functions shows that the modification of digit II in Chirostenotes possibly is related to the probing of crevices to apprehend prey. Such prey would have to be soft-bodied enough to impale and extract, small enough to extract with one claw, and large and/or abundant enough to sustain a predator with a manual modification that suggests specialization for said prey. The morphology of and range of motion in the hand of Chirostenotes are also compatible with a hooking function but not with digging or one-handed prehension.
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