scholarly journals New sphenodontian (Reptilia: Lepidosauria) from a novel Late Triassic paleobiota in western North America sheds light on the earliest radiation of herbivorous lepidosaurs

2021 ◽  
pp. 1-18
Author(s):  
Ben T. Kligman ◽  
Warren C. McClure ◽  
Mark Korbitz ◽  
Bruce A. Schumacher
Keyword(s):  
North America ◽  
Feeding Strategy ◽  
Phylogenetic Analyses ◽  
Global Radiation ◽  
Plant Macrofossils ◽  
Late Triassic ◽  
New Taxon ◽  
Western North America ◽  
Chinle Formation ◽  
Group Sharing

Abstract Herbivory is a common ecological function among extant lepidosaurs, but little is known about the origin of this feeding strategy within Lepidosauria. Here we describe a sphenodontian (Lepidosauria) from the Late Triassic of western North America, Trullidens purgatorii n. gen. n. sp., that reveals new aspects of the earliest radiation of herbivorous lepidosaurs. This taxon is represented by an isolated lower jaw with robust structure bearing transversely widened dentition and extensive wear facets, suggesting a masticatory apparatus specialized for herbivory. An unusual ‘incisor-like’ tooth is present at the anterior end of the jaw; a unique feature among lepidosaurs, this tooth is convergent with the incisors of extant rodents and lagomorphs. Phylogenetic analyses support the placement of this taxon within opisthodontian sphenodontians, a group sharing derived cranio-dental morphologies specialized for herbivory. The new taxon was recovered in a recently discovered and unnamed series of Upper Triassic strata in southeastern Colorado, USA, exposed in Canyons incised by the Purgatoire River and its tributaries. These strata comprise a dominantly red-bed sequence of conglomerates, sandstones, and siltstones deposited in a fluvio-lacustrine setting, preserving a Late Triassic biota of invertebrate and vertebrate ichnofossils, plant macrofossils, bony fish, temnospondyl amphibians, and reptiles. We use aetosaur osteoderms as biostratigraphic links to the nearby Chinle Formation of Arizona, USA, establishing a middle Norian age for these strata. The presence of an opisthodontian from western equatorial Pangaea in the Norian Stage reveals a near-global radiation of this clade across the Pangaean supercontinent during the Late Triassic. UUID: http://zoobank.org/A737c03f-863a-488e-a860-5cc914548774.

scholarly journals Cranial anatomy of Allosaurus jimmadseni, a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e7803 ◽  
Author(s):  
Daniel J. Chure ◽  
Mark A. Loewen
Keyword(s):  
New Species ◽  
North America ◽  
Phylogenetic Analyses ◽  
Upper Jurassic ◽  
Morrison Formation ◽  
Ventral Margin ◽  
Western North America ◽  
Theropod Dinosaur ◽  
Theropod Dinosaurs ◽  
A New Species

Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. The present study also assigns several other specimens to this new species, Allosaurus jimmadseni, which is characterized by a number of autapomorphies present on the dermal skull roof and additional characters present in the postcrania. In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni. The paired nasals of Allosaurus jimmadseni possess bilateral, blade-like crests along the lateral margin, forming a pronounced nasolacrimal crest that is absent in Allosaurus fragilis.

scholarly journals Redescription of Arundel formation Ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an “Ostrich Dinosaur”: Biogeographic implications

2016 ◽  
Author(s):  
Chase Doran Brownstein
Keyword(s):  
United States ◽  
North America ◽  
Early Cretaceous ◽  
Fossil Record ◽  
East Coast ◽  
The United States ◽  
Eastern North America ◽  
New Taxon ◽  
Western North America ◽  
The Past

The fossil record of dinosaurs from the Early Cretaceous of eastern North America is scant, and only a few sediments to the east of the continent are fossiliferous. Among them is the Arundel Formation of the east coast of the United States, which has produced among the best dinosaur faunas known from the Early Cretaceous of eastern North America. The diverse dinosaur fauna of this formation has been thoroughly discussed previously, but few of the dinosaur species originally described from the Arundel are still regarded as valid genera. Much of the Arundel material is in need of review and redescription. Among the fossils of dinosaurs from this formation are those referred to ornithomimosaurs. Here, I redescribe ornithomimosaur remains from the Arundel Formation which may warrant the naming of a new taxon of dinosaur. These remains provide key information on the theropods of the Early Cretaceous of Eastern North America. The description of the Arundel material herein along with recent discoveries of basal ornithomimosaurs in the past 15 years has allowed for comparisons with the coelurosaur Nedcolbertia justinhofmanni, suggesting the latter animal was a basal ornithomimosaurian dinosaur rather than a “generalized” coelurosaur. Comparisons between the Arundel ornithomimosaur and similar southeast Asian ornithomimosaurian material as well as ornithomimosaur remains from western North America suggest that a lineage of ornithomimosaurs with a metatarsal condition intermediate between that of basal and derived ornithomimosaurs was present through southeast Asia into North America, in turn suggesting that such animals coexisted with genera having a more primitive metatarsal morphology as seen in N. justinhofmanni.

Mitochondrial DNA variation in water shrews (Sorex palustris, Sorex bendirii) from western North America: implications for taxonomy and phylogeography

2005 ◽  
Vol 83 (11) ◽  
pp. 1469-1475 ◽  
Author(s):  
M B O'Neill ◽  
D W Nagorsen ◽  
R J Baker
Keyword(s):  
Mitochondrial Dna ◽  
North America ◽  
Phylogenetic Analyses ◽  
Sequence Divergence ◽  
Vancouver Island ◽  
Western North America ◽  
Cytb Sequence ◽  
Dna Variation ◽  
Late Pliocene ◽  
Postglacial Colonization

Inter- and intra-specific variations in cytochrome b (Cytb) sequence were assessed in 22 specimens of Sorex palustris Richardson, 1828 and 6 specimens of Sorex bendirii (Merriam, 1884) from 20 locations in western North America. Phylogenetic analyses revealed three distinct clades: Boreal (S. p. palustris), Cordilleran (S. p. brooksi, S. p. navigator), and Coastal (S. b. palmeri, S. b. bendirii). Sequence divergence between the Boreal and the Coastal–Cordilleran lineages was 6.9%, while the divergence between the Coastal and the Cordilleran clades was 3.1%. Sorex palustris brooksi, a subspecies endemic to Vancouver Island, showed minor divergence from mainland samples of S. p. navigator. The results suggest that S. palustris may consist of two species: a boreal eastern form (S. palustris) and a Cordilleran form (S. navigator). The taxonomic validity of S. p. brooksi is unresolved. Distribution of the three clades are consistent with vicariance and isolation in coastal, Cordilleran, and eastern refugia in the Late Pliocene or Pleistocene. The Vancouver Island subspecies S. p. brooksi is probably derived from postglacial colonization in the Late Pleistocene.

scholarly journals Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7551 ◽  
Author(s):  
Jeffrey W. Martz ◽  
Bryan J. Small
Keyword(s):  
Articular Surface ◽  
Upper Triassic ◽  
Late Triassic ◽  
New Taxon ◽  
Dietary Specialization ◽  
Sister Clade ◽  
Chinle Formation ◽  
Northern Colorado ◽  
Land Vertebrate ◽  
Early Late

The “red siltstone” member of the Upper Triassic Chinle Formation in the Eagle Basin of Colorado contains a diverse assemblage of dinosauromorphs falling outside of Dinosauria. This assemblage is the northernmost known occurrence of non-dinosaurian dinosauromorphs in North America, and probably falls within the Revueltian land vertebrate estimated biochronozone (215–207 Ma, middle to late Norian). Lagerpetids are represented by proximal femora and a humerus referable to Dromomeron romeri. Silesaurids (non-dinosaurian dinosauriforms) are the most commonly recovered dinosauromorph elements, consisting of dentaries, maxillae, isolated teeth, humeri, illia, femora, and possibly a scapula and tibiae. These elements represent a new silesaurid, Kwanasaurus williamparkeri, gen. et sp. nov., which possesses several autapomorphies: a short, very robust maxilla with a broad ascending process, a massive ventromedial process, a complex articular surface for the lacrimal and jugal, and 12 teeth; 14 dentary teeth; an ilium with an elongate and blade-like preacetabular process and concave acetabular margin; a femur with an extremely thin medial distal condyle and a depression on the distal end anterior to the crista tibiofibularis. The recognition of K. williamparkeri further demonstrates the predominantly Late Triassic diversity and widespread geographic distribution across Pangea of the sister clade to Asilisaurus, here named Sulcimentisauria. Silesaurid dentition suggests a variety of dietary specializations from faunivory and omnivory in the Middle Triassic and early Late Triassic (Carnian), to herbivory in the Late Triassic (Carnian and Norian), with the latter specialization possibly coinciding with the radiation of Sulcimentisauria across Pangea. The extremely robust maxilla and folidont teeth of K. williamparkei may represent a strong herbivorous dietary specialization among silesaurids.

scholarly journals A new species of Cybaeus L. Koch, 1868 (Araneae, Cybaeidae) with simple genitalia from central Japan is the sister species of C. melanoparvus Kobayashi, 2006 with elongated genitalia

2021 ◽  
Vol 97 (1) ◽  
pp. 223-233
Author(s):  
Yusuke Sugawara ◽  
Yoh Ihara ◽  
Takafumi Nakano
Keyword(s):  
New Species ◽  
North America ◽  
Lateral Surface ◽  
Phylogenetic Analyses ◽  
Mitochondrial Gene ◽  
Sister Species ◽  
Western North America ◽  
Central Japan ◽  
Gene Markers ◽  
A New Species

Spiders of the genus Cybaeus L. Koch, 1868 exhibit two major centers of diversity: Western North America and Japan. Several Japanese Cybaeus possess an elongated embolus in the male palp and elongated tubular spermathecae in the female genitalia. Here we describe Cybaeus koikeisp. nov. from central Honshu, Japan, which has an unelongated embolus and bulbous spermathecae. Phylogenetic analyses using nuclear and mitochondrial gene markers clearly support the monophyly of C. koikeisp. nov. and Cybaeus melanoparvus Kobayashi, 2006, a species with elongated genitalia. Both species share a similar habitus and a cluster of robust setae on the lateral surface of the male palpal patella. The latter is considered a synapomorphy for C. koikeisp. nov. and C. melanoparvus. A supplementary description of the spermathecae of C. melanoparvus is also provided.

Late Triassic dasycladacean alga from northeastern Oregon: significance of first reported occurrence in western North America

1989 ◽  
Vol 63 (3) ◽  
pp. 374-381 ◽  
Author(s):  
Erik Flügel ◽  
Baba Senowbari-Daryan ◽  
George D. Stanley
Keyword(s):  
United States ◽  
North America ◽  
Western Europe ◽  
The United States ◽  
Upper Triassic ◽  
Late Triassic ◽  
Western North America ◽  
Dispersal Abilities ◽  
Wallowa Terrane ◽  
Fossil Alga

An Upper Triassic metaspondyle dasycladacean alga,Diplopora oregonensisn. sp., is described from the Hurwal Formation, southern Wallowa Mountains, northeastern Oregon. It occurs in the accreted Wallowa terrane, which is interpreted as far-travelled relative to the craton of North America. The fossil alga is found in limestone clasts within a limestone–chert–volcanic clast conglomerate of the Hurwal Formation. The new species is related toDiploplora borzaiBystricky, known from the Upper Triassic of the Carpathian Mountains and Sicily, but is distinguished by very small branches and a distinct segmentation of the thalli.Diplopora oregonensisis the first Triassic dasycladacean alga known from the United States, and perhaps from all of North America. The absence of calcareous green algae from rocks of cratonal North America, as well as from most Triassic displaced terranes of the eastern and western Pacific, is in stark contrast to counterparts in the former Tethys region of central Europe, where dasycladacean algae were abundant and contributed significantly to the sediment. This paucity of algae may be related to differences in environment, but more likely is linked to the paleogeographic situation and dispersal abilities of the algae. The similarity of the Oregon dasyclads to species in western Europe, coupled with the lack of dasyclad algae in any other part of North America, is evidence in support of a far-travelled nature for the Wallowa terrane.

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