Showing papers in "Journal of Vertebrate Paleontology in 1981"
TL;DR: It is concluded that the fossil jawless Craniata provide little information on the affinities of the CraniATA, but they do provide complementary data on distribution of characters.
Abstract: The phylogenetic relationships of the extant Craniata are analyzed, and the position of the best known fossil groups of jawless craniates is discussed. Some of the patterns obtained are inconsistent with previous opinions on the phylogeny of the Craniata, e.g. on the question of monophyly of the Cephalaspidomorphi. It is concluded that the fossil jawless Craniata provide little information on the affinities of the Craniata, but they do provide complementary data on distribution of characters. According to their respective positions in the cladogram, these fossil groups allow determination of polarity of some characteristics, such as paired fins, naso-hypophysial complex, and eye musculature.
206 citations
TL;DR: A large slab of arenaceous siltstone was collected from strata of the Gething Formation (Aptian, Lower Cretaceous) in the Peace River Canyon of northeastern British Columbia, Canada, and more than 200 footprints between 2.0 and 4.4 cm in length were found on a single bedding plane within the slab as discussed by the authors.
Abstract: A large slab of arenaceous siltstone was collected from strata of the Gething Formation (Aptian, Lower Cretaceous) in the Peace River Canyon of northeastern British Columbia, Canada. More than 200 footprints between 2.0 and 4.4 cm in length were found on a single bedding plane within the slab. These were made by a minimum of four individuals that apparently were feeding. The footprints have an average divarication of 113° and a correlated width to length ratio of 1.26, which fall within the range encountered in birds. Divarication between digits II and IV in even the smallest dinosaurs never exceeds 100° on an average per trackway. Other characteristics support the identification of these tracks from the Peace River Canyon as having been made by birds. The new genus and species, Aquatilavipes swiboldae, is the earliest known record of bird footprints, and probably represents a primitive taxon of marsh-dwelling bird.
80 citations
TL;DR: Chasmaporthetes ossifragus is recognized as the most derived taxon as discussed by the authors, and the fossil record suggests immigration of this genus from Eurasia to North America prior to 3.5 mya.
Abstract: Maxillary fragments, rami, and postcrania referred to the hyaenid Chasmaporthetes ossifragus are recorded from two Florida faunas, Santa Fe River (probably late Blancan) and Inglis IA (early Irvingtonian). C. ossifragus with its reduced premolars, deep mandible, and long blade-like carnassials probably filled the ecologic role of an active predator occupied today by the spotted hyaena, Crocuta. The fore and hind quarters of the hunting hyaena were heavily muscled and its elongate limbs and feet suggest that it was well adapted for cursorial life. Review of the phylogenetic history of the group suggests that Asian C. kani, European C. lunensis, and North American C. ossifragus and C. johnstoni are all closely related. C. ossifragus is recognized as the most derived taxon. The fossil record suggests immigration of this genus from Eurasia to North America prior to 3.5 mya. Chasmaporthetes became extinct in Eurasia during the late Villafranchian and survived in North America into the early Irvingtonian.
60 citations
TL;DR: Aerosaurus wellesi n. sp. is based upon two nearly complete articulated skeletons from the Lower Permian deposits near Arroyo del Agua, New Mexico as mentioned in this paper.
Abstract: Aerosaurus wellesi n. sp. is based upon two nearly complete articulated skeletons from the Lower Permian deposits near Arroyo del Agua, New Mexico. Study of these superbly preserved specimens indicates that the genus Aerosaurus is distinguishable from most other pelycosaurs, including Varanops and Varanodon, in having fewer maxillary and dentary teeth, all of which are more laterally compressed and more strongly recurved. The parasphenoid is uniquely expanded laterally and posteriorly, and bears rows of teeth on ridges. Aerosaurus also differs from all other pelycosaurs in which the braincase is adequately known in the formation of the dorsum sellae mainly from the basisphenoid. Aerosaurus was probably an aggressive predator of lizard-like habitus, with an unusually long tail for a pelycosaur. Aerosaurus, Varanops, and Varanodon are the only pelycosaurs that can be included in the family Varanopseidae with certainty; however, Basicranodon may also be a varanopseid. The possibility that the allege...
55 citations
TL;DR: Early and middle Tiffanian samples reveal a significant drop in both species richness and evenness, with predominance of one or two species; but diversity may have increased in the late Tiffanian.
Abstract: Sixteen mammalian assemblages from the middle Paleocene (Torrejonian) to early Eocene (Wasatchian) of western North America have been studied to determine their species composition and diversity. Torrejonian and Tiffanian faunas are dominated by small mammals of archaic aspect, while larger forms predominate in Clarkforkian assemblages and remain common in the Wasatchian. Both Clarkforkian and Wasatchian faunas are characterized by immigrant taxa, including representatives of more modern groups of mammals. Torrejonian assemblages have many species, and species abundances are relatively equitably distributed. Early and middle Tiffanian samples reveal a significant drop in both species richness and evenness, with predominance of one or two species; but diversity may have increased in the late Tiffanian. Clarkforkian assemblages resemble early-middle Tiffanian ones in their low species richness and evenness. Wasatchian assemblages, however, are somewhat richer in species and show much greater equita...
54 citations
TL;DR: Nearly 4000 hybodontoid teeth assignable to the typically Mesozoic genera Acrodus and Polyacrodus were recovered by bulk-sampling techniques from the Early Permian Wichita-Albany Group in north-central Texas, belonging to 37 local faunas.
Abstract: Nearly 4000 hybodontoid teeth assignable to the typically Mesozoic genera Acrodus and Polyacrodus were recovered by bulk-sampling techniques from the Early Permian Wichita-Albany Group in north-central Texas. They belong to 37 local faunas. Generic assignments are based mainly on crown histology, following the methods of earlier workers. This approach must suffice until the suborder can be revised using a new methodology, yet to be devised. The roots of all the teeth bear specialized foramina on the labial side, parallel to the root-crown contact. The teeth questionably assigned to Acrodus have roots morphologically different from those of Mesozoic species. Hybodus is absent. Tooth morphotypes are assigned to six new species: ?A. olsoni (large teeth with symmetrical crowns; dentition moderately hetero-dont), ?A. sweetlacruzensis (arcuate root-crown contact; roots with deep, closed sulcus; dentition tion homodont), P. zideki (teeth small; crowns uncrenulated, possess longitudinal and transverse oc...
54 citations
TL;DR: The skeleton of Mesoscalops montanensis is more complete than that of any proscalopid known to date, and provides a basis for description of the previously unknown vertebral column, ribs, articulated forelimb.
Abstract: A nearly complete and partially articulated skeleton of Mesoscalops, a genus of fossorial insectivore hitherto known only by isolated teeth and some bones of the forelimb, is described and compared with other proscalopids, talpids, and chrysochlorids. The skeleton (UWBM 54708) is more complete than that of any proscalopid known to date, and provides a basis for description of the previously unknown vertebral column, ribs, articulated forelimb including the scapula, clavicle, manubrium, pelvis, femur, fibula, astragalus, and metatarsals. UWBM 54708, from the Hemingfordian or Barstovian Deep River Formation, Meagher County, Montana, represents a new species, M. montanensis. The skull of M. montanensis more closely resembles Whitneyan than late Arikareean proscalopids, suggesting that Mesoscalops was derived from a Whitneyan form of Proscalops. The morphology of proscalopids, as exemplified by Mesoscalops montanensis, reflects a unique digging stroke and differs from that of talpids to a greater deg...
39 citations
TL;DR: An analysis of the functional morphology of the skull of Teratomis merriami indicates that these giant flying birds were predaceous carnivores as mentioned in this paper, which contrasts with prior assumptions that teratorns were scavengers like vultures.
Abstract: An analysis of the functional morphology of the skull of Teratomis merriami indicates that these giant flying birds were predaceous carnivores. This contrasts with prior assumptions that teratorns were scavengers like vultures. The large wingspans of teratorns limited them to savanna habitats. Teratorns probably originated in South America, sharing the dominance of the carnivore adaptive zone in the Tertiary of South America with the better known cursorial carnivorous birds collectively referred to as phorusrhacoids. Their evolution to such large flying birds was most likely directly tied to the progressive development of widespread savanna habitat in South America during the Tertiary. The soaring manner of flight of teratorns may have prevented their dispersal into North America until after the closure of the Central American land bridge. Expansion of savanna habitats in the Americas during Pleistocene glacial periods probably aided this dispersal.
34 citations
TL;DR: The holotype of the small sauropod dinosaur Astrodon pusillus from the Kimmeridgian (Upper Jurassic) of Portugal is shown to be the remains of a juvenile individual of the stegosaur Dacentrurus.
Abstract: The holotype of the small sauropod dinosaur Astrodon pusillus Lapparent and Zbyszewski, 1957, from the Kimmeridgian (Upper Jurassic) of Portugal is shown to be the remains of a juvenile individual of the stegosaur Dacentrurus. The records of Astrodon from the Upper Jurassic of North America and the Lower Cretaceous of Africa are based on material of juvenile sauropods. However, teeth from the Lower Cretaceous of Portugal are correctly referred to Astrodon as A. valdensis (Lydekker). A review is presented of the intercontinental genera that the Late Jurassic and Early Cretaceous faunas of Western Europe shared with faunas of corresponding ages in North America and Africa.
26 citations
TL;DR: Ibispagana Milne-Edwards from the early Miocene of France is assigned to the living genus Plegadis, and the only valid Tertiary paleospecies of Threskiornithidae is considered to be Aves incertae sedis.
Abstract: On the basis of characters of the tarsometatarsus, Ibispagana Milne-Edwards from the early Miocene of France is assigned to the living genus Plegadis. Plegadis gracilis A. H. Miller and Bowman, 1956, from the late Pliocene of North America, is a junior homonym of Milnea (=Plegadis) gracilis Lydekker, 1891, and the new name Plegadis pharangites is proposed as a substitute. Plegadis paganus and P. pharangites constitute the only valid Tertiary paleospecies of Threskiornithidae. All other extinct taxa that have been referred to this family are here considered to be Aves incertae sedis except for Theristicus wetmorei Campbell and Eudodmus peruvianus Campbell, from the late Pleistocene of Peru, and the flightless Quaternary taxa Aptertbis glenos Olson and Wetmore of Hawaii and Xenicibis xympithecus Olson and Steadman of Jamaica.
24 citations
TL;DR: The dental morphology of Repomys is much more similar to Nelsonia neotomodon Merriam from the living fauna of Mexico, and this similarity suggests an ancestor-descendant relationship.
Abstract: Repomys is a new genus of hypsodont cricetine from the late Neogene of California and Nevada. Three new species define its known temporal and geographic distribution: Repomys gustelyi n. sp. (type species), late Hemphillian, Mojave Desert, California; Repomys maxumi n. sp., early Blancan, San Francisco Bay area, California; and Repomys panacaensis n. sp., middle Blancan, southeastern Nevada. Repomys resembles the “wood rats” in development of hypsodonty, but this resemblance is the result of parallel evolution. The dental morphology of Repomys is much more similar to Nelsonia neotomodon Merriam from the living fauna of Mexico, and this similarity suggests an ancestor-descendant relationship.
TL;DR: A pterosaurian cervical vertebra, fragment of humerus, and associated femur and tibia from the Merchantville Formation (early Campanian, Late Cretaceous) of northern Delaware provide the second record of flying reptiles in eastern North America as mentioned in this paper.
Abstract: A pterosaurian cervical vertebra, fragment of humerus, and associated femur and tibia from the Merchantville Formation (early Campanian, Late Cretaceous) of northern Delaware provide the second record of Cretaceous flying reptiles in eastern North America. These bones resemble Pteranodon in morphology and size but are not securely assignable to a particular genus of the family Ornithocheiridae. Comparison with Pteranodon skeletons from the Niobrara Chalk of Kansas indicates a wingspan of about 5.8 m (19 ft) for the Delaware pterosaurs. The successive Upper Cretaceous reptile faunas of the Merchantville, Marshalltown, and Mount Laurel Formations along the Chesapeake and Delaware Canal are listed for the first time.
TL;DR: A new genus Texomys is recorded from late Hemingfordian and Barstovian deposits of the Texas Coastal Plain and from early Heminghamfordian deposits in Panama.
Abstract: A new genus Texomys is recorded from late Hemingfordian and Barstovian deposits of the Texas Coastal Plain and from early Hemingfordian deposits of Panama. The Panamanian T. stewardi is the smallest species of the genus; the Texas Barstovian T. ritchiei (type species) is the largest; and the Texas late Hemingfordian specimens of Texomys sp. are intermediate in size. The genus apparently is not present in early Hemingfordian deposits of the Texas Coastal Plain. This suggests that it originated in Latin North America and appeared on the Texas Coastal Plain during the late Hemingfordian, while continuing a size increase trend. Thus far, Texomys has not been recovered from Clarendonian deposits of Texas.
TL;DR: Some structural characters of bone annulation in the fossil crocodile appear to be related to the existence of seasons during the middle Eocene in Wyoming and suggest a yearly alternation of a cool and dry season with a warm and wet one.
Abstract: The Yale Peabody Museum skull YPM 511 from the middle Eocene Bridger beds of Wyoming belongs to the crocodylid Crocodylus cf. affinis Marsh, 1871. Its general histological characters, particularly the organization of the skeletal growth lines, resemble closely those of a C. niloticus of the same size. Growth-line counts in both specimens allow ontogenic age estimates that are consistent with the available curves of size/age relationship for the genus Crocodylus. As in living crocodilians, some structural characters of bone annulation in the fossil crocodile appear to be related to the existence of seasons during the middle Eocene in Wyoming and suggest a yearly alternation of a cool and dry season with a warm and wet one.
TL;DR: Kyptoceras amatorum is described from the Upper Bone Valley Formation, late Hemphillian (early Pliocene) of Polk County, Florida, which may have originated in subtropical savannas south of the range of the more familiar tribe Synthetoceratini.
Abstract: Kyptoceras amatorum n.g. et sp. is described from the Upper Bone Valley Formation, late Hemphillian (early Pliocene) of Polk County, Florida. In the male skull the forked rostral horn lacks a shaft and the frontal horns are nearly twice as long as those of any other Protoceratidae. Both the rostral and the frontal horns are tilted forward in distinctive fashion. This genus represents a new tribe, Kyptoceratini, which may have originated in subtropical savannas south of the range of the more familiar tribe Synthetoceratini.
TL;DR: The Mouth of McCann's Canyon Site represents an eastern extension of the Harrison Formation in Cherry County, Nebraska, and provides the earliest North American records of the modern lizard genus Eumeces, and of the snake family Viperidae.
Abstract: The Mouth of McCann's Canyon Site represents an eastern extension of the Harrison Formation (early Miocene: Arikareean) in Cherry County, Nebraska. At least one anuran, one turtle, three lizards, and six snakes are present. The fauna provides the earliest North American records of the modern lizard genus Eumeces, and of the snake family Viperidae. Two new lizards are described: Harrisonsaurus fossilis gen. et sp. n., of uncertain familiar status, and Eumeces antiquus sp. n. of the family Scincidae. The teeth of Harrisonsaurus have bulbous tips separated from the remainder of the crowns by constricted necks. With the exception of a single viperid, the snake fauna is a typical early Miocene one, consisting of five small boids. A cervical vertebra of the extinct boid genus Geringophis is described and figured for the first time.
TL;DR: Two isolated vertebrae of the giant aquatic snake Pterosphenus schucherti Lucas were recently discovered in deposits of the late Eocene Jackson Group near Forrest City, Arkansas.
Abstract: Two isolated vertebrae of the giant aquatic snake Pterosphenus schucherti Lucas were recently discovered in deposits of the late Eocene Jackson Group near Forrest City, Arkansas. This is the first record of the species in deposits of the Mississippi Embayment, and its westernmost occurrence in North America. The fauna associated with the Arkansas specimens of P. schucherti contains marine, freshwater, and terrestrial forms indicative of estuarine environment. A review of the faunas associated with the previously reported specimens of P. schucherti also indicates that their burial occurred under hyposaline conditions. This implies that P. schucherti inhabited Eocene estuaries rather than seas.
TL;DR: A new species of thick-knee is described from the early Miocene (Sheep Creek Formation, late Hemingfordian) of Nebraska, providing the first Tertiary record of the Burhinidae, and it is suggested that Burhinus lucorum may have inhabited stream-side woodlands.
Abstract: A new species of thick-knee, Burhinus lucorum, is described from the early Miocene (Sheep Creek Formation, late Hemingfordian) of Nebraska, providing the first Tertiary record of the family. Contrary to the widely held view that thick-knees are necessarily indicative of dry, sparsely vegetated country, the extant species of Burhinidae in fact live in a broad range of habitats. Thus, the use of extinct species of Burhinidae as paleoclimatological indicators is compromised. Evidence from other sources on early Miocene climates is summarized and suggests that Burhinus lucorum may have inhabited stream-side woodlands.
TL;DR: Palaeostruthus hatcheri (Shufeldt) is the oldest known species of Emberizidae as mentioned in this paper, from the late Miocene (late Clarendonian-early Hemphillian) Long Island local fauna, Kansas.
Abstract: Palaeostruthus hatcheri (Shufeldt), from the late Miocene (late Clarendonian-early Hemphillian) Long Island local fauna, Kansas, is the oldest recorded species of Emberizidae. The holotype and only specimen of P. hatcheri is a complete rostrum which, upon re-examination, is seen to be extremely similar to that of Ammodramus savannarum, the living grasshopper sparrow. Therefore, the genus Palaeostruthus Wetmore is synonymized with Ammodramus Swainson. Aside from A. hatcheri, the only other supposed species of Palaeostruthus is P. eurius Brodkorb, which is known only from a distal end of tarsometatarsus and should be known as “Passeriformes, family and genus indet.” until re-examined.
TL;DR: New fossils from the Deep River Formation, Meagher County, Montana, add to our knowledge of aplodontid evolution in the Rocky Mountain region as discussed by the authors, and represent a series ranging from brachyodont to rather strongly hypsodont forms.
Abstract: New fossils from the Deep River Formation, Meagher County, Montana, add to our knowledge of aplodontid evolution in the Rocky Mountain region. The new material shows much greater diversity than was indicated by the single species previously known. At least four groups, Niglarodon koemeri, N. progressus n. sp., N. blacki n. sp., and N. loneyi n. sp., represent a series ranging from brachyodont to rather strongly hypsodont forms. Stratigraphic and local geographic differences of occurrence indicate a chronologic succession. The diversity of morphology and apparent regional endemism suggest an early dispersal followed by extensive geographic partitioning. After initial settlement, subsequent histories in different subregions of the Rocky Mountains involve appearance of characters of rather proximal origin, as well as introduction of characters which seem to be derived from more distant populations of the region. Interregional immigration between the Rocky Mountains and the West Coast did not occur. ...
TL;DR: An enigmatic new genus and species of emberizine finch, Pedinorhis stirpsarcana, is known from four cave deposits of probable Wisconsinan age in central Puerto Rico and, although of uncertain affinities, somewhat resembles the mainland genera Atlapetes and Pipilo.
Abstract: Pedinorhis stirpsarcana, an enigmatic new genus and species of emberizine finch, is known from four cave deposits of probable Wisconsinan age in central Puerto Rico. The most distinctive feature of this bird is the broad, flat ridge of the rostrum. Pedinorhis represents a group unknown in the Antilles and, although of uncertain affinities, somewhat resembles the mainland genera Atlapetes and Pipilo. The disappearance of Pedinorhis may be related to the postglacial loss of arid, savanna-like habitats that caused the extinction, or contraction in range, of many xerophilous vertebrates in the West Indies.
TL;DR: Urenchelys abditus represents the first authentic record of a Cretaceous eel from North America and differs from other species of the genus from the English Chalk and Lebanon in having fewer vertebrae between the anterior insertion of the anal fin and thinner skull roofing bones.
Abstract: Urenchelys abditus n. sp. represents the first authentic record of a Cretaceous eel from North America. “Anguillavus” hackberryensis Martin is not an eel, but probably a dercetid. Urenchelys resembles Recent eels in lacking pelvic fins, but resembles the Cretaceous genus Anguillavus in having a separate caudal fin. Urenchelys may or may not be a monophyletic group, the species are not known to share a derived character common only to themselves. Urenchelys abditus differs from other species of the genus from the English Chalk and Lebanon in having fewer vertebrae between the anterior insertion of the anal fin and (in the case of U. anglicus) thinner skull roofing bones. The only referred specimen was found in a pelecypod shell.
TL;DR: Mancalla emlongi, new species, is the fifth species described in this extinct genus of flightless auks and is the third to be described from the late Pliocene San Diego Formation of southern California.
Abstract: Mancalla emlongi, new species, is the fifth species described in this extinct genus of flightless auks and is the third to be described from the late Pliocene San Diego Formation of southern California. The species is based on a right ulna that is markedly larger than in any other member of the genus.
TL;DR: The growth pattern of rodent incisors closely approximates a segment of a circle and can be described graphically by measuring the radius of that circle and the length of the segment in degrees (subtended angle).
Abstract: The growth pattern of rodent incisors closely approximates a segment of a circle and can be described graphically by measuring the radius of that circle (radius of curvature) and the length of the segment in degrees (subtended angle). When tested on specimens from a modern owl pellet accumulation, this method yielded consistent results and suggested that both the radius of curvature and subtended angle increase during ontogeny. Potential applications include improved identification and description of isolated incisors, studies of population age structure, and interpreting the evolution of incisor procumbency.
TL;DR: A new combination of Lep-tomeryx semidnctus and Hypertragulus transversus, each originally based on a single tooth from the Chadronian Cypress Hills Formation of Saskatchewan, and a new species, Pseudoprotoceras tayhri, based on Wyoming material are described.
Abstract: Pseudoprotoceras semidnctus, new combination, includes Cope's species Lep-tomeryx semidnctus and Hypertragulus transversus, each originally based on a single tooth from the Chadronian Cypress Hills Formation of Saskatchewan. New topotypic material, and referred material from Wyoming, allow description of the complete dental series, and show some cranial and mandibular features. A new species, Pseudoprotoceras tayhri, is based on Wyoming material. Pseudoprotoceras semidnctus occurs in the early to medial Chadronian, and P. taytori in the later Chadronian.
TL;DR: In this paper, the basic structure and evolution of vertebrates are discussed and a review of E. Jarvik's work is presented. But the review is limited to the basic structures and evolution.
Abstract: (1981). Review of E. Jarvik, ‘Basic Structure and Evolution of Vertebrates’. Journal of Vertebrate Paleontology: Vol. 1, No. 3-4, pp. 389-397.
TL;DR: Recently discovered specimens indicate that the dental formula of Stylinodon is l2 1 C1 1 P4 4 M3 3, thus, contrary to previous opinions, Ectoganus can be excluded from the direct ancestry of Styinodon.
Abstract: Stylinodon, the latest taeniodont, is known from the late Wasatchian and Bridgerian of Colorado and Wyoming, Uintan of Utah, and Bridgerian or Uintan of western Texas. Two species, S. mirus Marsh, 1874, and S. inexplicatus, new species, are here considered valid. A large gliriform tooth from the late Eocene of Shandong, China, formerly referred to “?Stylinodon”, is here referred to the Tillodontia. Recently discovered specimens indicate that the dental formula of Stylinodon is l2 1 C1 1 P4 4 M3 3. Thus, contrary to previous opinions, Ectoganus (dental formula I1 1 C1 1 P4 4 M3 3) can be excluded from the direct ancestry of Stylinodon.
TL;DR: In this paper, a new species of Geomys (Nerterogeomys) anzensis n. (Geomys arenarius) resembles G. garbanii in size and proportions of the skull, possibly implying an ecomorphic relationship.
Abstract: Geomyids have been recovered from 1,693 m of section, temporally ranging from mid-Blancan (Pliocene) to early Irvingtonian (Pleistocene). They are represented by Geomys (Nerterogeomys) anzensis n. sp., G. garbanii, and Thomomys sp. The new species resembles G. (Geomys) arenarius in size and proportions of the skull, possibly implying an ecomorphic relationship. The difference in size between G. anzensis and G. garbanii may explain the coexistence of these two species through a large part of the stratigraphic section, by implying two different pocket gopher habitats.