Postcranial skeleton ofUkhaatherium nessovi(Eutheria, Mammalia) from the Late Cretaceous of Mongolia

2003 ◽  
Vol 23 (4) ◽  
pp. 857-868 ◽  
Author(s):  
Inés Horovitz
Keyword(s):  
Late Cretaceous ◽  
Postcranial Skeleton

scholarly journals A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5016 ◽  
Author(s):  
Jelle P. Wiersma ◽  
Randall B. Irmis
Keyword(s):  
Late Cretaceous ◽  
First Record ◽  
Multiple Time ◽  
New Taxon ◽  
Postcranial Skeleton ◽  
Surface Textures ◽  
Close Phylogenetic Relationship ◽  
Biogeographic Provinces ◽  
Dispersal Events ◽  
Upper Campanian

A partial ankylosaurid skeleton from the upper Campanian Kaiparowits Formation of southern Utah is recognized as a new taxon, Akainacephalus johnsoni, gen. et sp. nov. The new taxon documents the first record of an associated ankylosaurid skull and postcranial skeleton from the Kaiparowits Formation. Preserved material includes a complete skull, much of the vertebral column, including a complete tail club, a nearly complete synsacrum, several fore- and hind limb elements, and a suite of postcranial osteoderms, making Akainacephalus johnsoni the most complete ankylosaurid from the Late Cretaceous of southern Laramidia. Arrangement and morphology of cranial ornamentation in Akainacephalus johnsoni is strikingly similar to Nodocephalosaurus kirtlandensis and some Asian ankylosaurids (e.g., Saichania chulsanensis, Pinacosaurus grangeri, and Minotaurasaurus ramachandrani); the cranium is densely ornamented with symmetrically arranged and distinctly raised ossified caputegulae which are predominantly distributed across the dorsal and dorsolateral regions of the nasals, frontals, and orbitals. Cranial caputegulae display smooth surface textures with minor pitting and possess a distinct conical to pyramidal morphology which terminates in a sharp apex. Character analysis suggests a close phylogenetic relationship with N. kirtlandensis, M. ramachandrani, Tarchia teresae, and S. chulsanensis, rather than with Late Cretaceous northern Laramidian ankylosaurids (e.g., Euoplocephalus tutus, Anodontosaurus lambei, and Ankylosaurus magniventris). These new data are consistent with evidence for distinct northern and southern biogeographic provinces in Laramidia during the late Campanian. The addition of this new ankylosaurid taxon from southern Utah enhances our understanding of ankylosaurid diversity and evolutionary relationships. Potential implications for the geographical distribution of Late Cretaceous ankylosaurid dinosaurs throughout the Western Interior suggest multiple time-transgressive biogeographic dispersal events from Asia into Laramidia.

A new, remarkably preserved, enantiornithine bird from the Upper Cretaceous Qiupa Formation of Henan (central China) and convergent evolution between enantiornithines and modern birds

2021 ◽  
pp. 1-8
Author(s):  
Li Xu ◽  
Eric Buffetaut ◽  
Jingmai O’Connor ◽  
Xingliao Zhang ◽  
Songhai Jia ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Convergent Evolution ◽  
Upper Cretaceous ◽  
Henan Province ◽  
Central China ◽  
Postcranial Skeleton ◽  
Cretaceous Period ◽  
New Evidence ◽  
Partial Skeleton

Abstract A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.

A new specimen of Suzhousaurus megatherioides (Dinosauria: Therizinosauroidea) from the Early Cretaceous of northwestern China

2008 ◽  
Vol 45 (7) ◽  
pp. 769-779 ◽  
Author(s):  
Da-qing Li ◽  
Hai-lu You ◽  
Jian-ping Zhang
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Lower Cretaceous ◽  
Inner Mongolia ◽  
Anterior Margin ◽  
Cladistic Analysis ◽  
Gansu Province ◽  
Northwestern China ◽  
Postcranial Skeleton ◽  
Left Half

A new specimen of a therizinosauroid dinosaur recovered from the Lower Cretaceous Xinminpu Group in the Yujingzi Basin of the Jiuquan area, Gansu Province, northwestern China, consists of a partial postcranial skeleton, including a well-preserved left half of the pelvic girdle. It is referred to Suzhousaurus megatherioides Li et al., 2007 based on the autapomorphic anterior concavity of its pubic shaft and is the second known specimen of this taxon. Comparisons of the structure of therizinosauroid pelvic girdles show that the pelvis of Suzhousaurus possesses several unique features, including a laterally deflected, thin, and flat preacetabular process of the ilium, a smoothly curved anterodorsal margin of the preacetabular process of the ilium, and a concave anterior margin of the pubic shaft. Cladistic analysis confirms that Suzhousaurus is more derived than the Early Cretaceous therizinosauroids Falcarius and Beipiaosaurus , less derived than Late Cretaceous forms, and likely closely related to Alxasaurus from the Early Cretaceous of Inner Mongolia, China.

scholarly journals Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile

2021 ◽  
Author(s):  
Sergio Soto-Acuña ◽  
Alexander Vargas ◽  
Jonatan Kaluza ◽  
Marcelo Leppe ◽  
Joao Botelho ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Phylogenetic Analyses ◽  
Heavy Tail ◽  
Postcranial Skeleton ◽  
Distal Half

Abstract Armoured dinosaurs are well known for forms that evolved specialized tail weapons: paired tail spikes in stegosaurs, and heavy tail clubs in advanced ankylosaurs1. Armoured dinosaurs from southern Gondwana are rare and enigmatic, but likely include the earliest branches of Ankylosauria2-4. Here, we describe a mostly complete, semiarticulated skeleton of a small (about 2m) armoured dinosaur from the late Cretaceous of Magallanes in southernmost Chile, a region biogeographically related to West Antarctica5. Stegouros elengassen gen. et sp. nov. evolved a large tail weapon unlike any dinosaur: A flat, frond-like structure formed by 7 pairs of laterally projecting osteoderms encasing the distal half of the tail. Stegouros shows ankylosaurian cranial characters, but a largely primitive postcranial skeleton, with some stegosaur-like characters. Phylogenetic analyses placed Stegouros in Ankylosauria, and specifically related to Kunbarrasaurus from Australia6 and Antarctopelta from Antarctica7, forming a clade of Gondwanan ankylosaurs that split earliest from all other ankylosaurs. Large osteoderms and specialized tail vertebrae in Antarctopelta suggest it had a tail weapon similar to Stegouros. We propose a new clade, the Parankylosauria, to include the first ancestor of Stegouros but not Ankylosaurus, and all descendants of that ancestor.

Morphological and phylogenetic aspects of the dentition of Megacephalosaurus eulerti, a pliosaurid from the Turonian of Kansas, USA, with remarks on the cranial anatomy of the taxon

2018 ◽  
Vol 156 (07) ◽  
pp. 1201-1216 ◽  
Author(s):  
DANIEL MADZIA ◽  
SVEN SACHS ◽  
JOHAN LINDGREN
Keyword(s):  
Late Cretaceous ◽  
Phylogenetic Relationships ◽  
Upper Cretaceous ◽  
Search Strategy ◽  
Tree Search ◽  
Postcranial Skeleton ◽  
Cross Sectional ◽  
Phylogenetic Studies ◽  
Sectional Shape ◽  
Tooth Count

AbstractMegacephalosaurus eulerti is a large macropredatory plesiosaur representing one of the last members of the diverse pliosaurid clade Brachaucheninae. The taxon was established upon a nearly complete skull including the mandible and fragments of the postcranial skeleton originating from the lower middle Turonian (Upper Cretaceous) of Kansas, USA. Owing to its age, reasonable completeness and its state of preservation, M. eulerti bears important anatomical details regarding the last brachauchenines. Here we assess the dentition of the taxon, compare the teeth to those of other thalassophonean pliosaurids and comment on the utility of these results for inferences of the phylogenetic relationships of the last brachauchenines. Additionally, we provide remarks on the cranial anatomy of M. eulerti, revise character scores of this taxon used in current phylogenetic studies and address the phylogenetic relationships within Brachaucheninae. Parsimony analyses, aimed to test different character sampling and tree-search strategy, inferred only a single unambiguous synapomorphy uniting a clade formed by mid- to Late Cretaceous brachauchenines: presence of subcircular rather than subtrihedral/trihedral cross-sectional shape of the teeth. Still, the last brachauchenines (Brachauchenius and Megacephalosaurus) can be roughly characterized by a switch from anisodont to subisodont dentition and reduction of their tooth count. Nevertheless, the overall knowledge of the origin, phylogenetic relationships and distinguishability of brachauchenine pliosaurids remains poor and represents a subject for further extensive studies and modifications in taxon and character sampling.

Marine turtles from the Late Cretaceous of Alberta, Canada

2015 ◽  
Vol 52 (8) ◽  
pp. 581-589 ◽  
Author(s):  
Donald B. Brinkman ◽  
Michael Densmore ◽  
Márton Rabi ◽  
Michael J. Ryan ◽  
David C. Evans
Keyword(s):  
Late Cretaceous ◽  
Postcranial Skeleton ◽  
Crown Group ◽  
Marine Turtles ◽  
Additional Information ◽  
Dinosaur Park Formation ◽  
Freshwater Environments

Previously reported and new specimens of marine turtles from the late Campanian of Alberta, Canada, provide additional information on the diversity and distribution of chelonioid turtles at this time. An articulated carapace from the Bearpaw Formation previously interpreted as Lophochelys niobrarae is considered to be a juvenile of a specifically indeterminate chelonioid and is referred to Lophochelys sp. Isolated neurals and a hyoplastron from nonmarine estuarine deposits in the uppermost beds of the Dinosaur Park Formation are tentatively referred to Lophochelys sp. These specimens suggest that this chelonioid could enter freshwater environments. A new chelonioid, Kimurachelys slobodae gen. et sp. nov., is recognized on the basis of two mandibles and a maxilla from the uppermost beds of the Dinosaur Park Formation of southeastern Alberta. A partial postcranial skeleton of an indeterminate chelonioid from the Bearpaw Formation provides additional evidence that chelonioids of this formation included taxa that were phylogenetically intermediate between chelonioids of the late Santonian and members of the crown group.

scholarly journals A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia

2013 ◽  
Vol 280 (1766) ◽  
pp. 20131186 ◽  
Author(s):  
Scott D. Sampson ◽  
Eric K. Lund ◽  
Mark A. Loewen ◽  
Andrew A. Farke ◽  
Katherine E. Clayton
Keyword(s):  
Phylogenetic Analysis ◽  
North America ◽  
Late Cretaceous ◽  
Fossil Record ◽  
Strong Support ◽  
Northern Region ◽  
New Taxon ◽  
Western North America ◽  
Postcranial Skeleton ◽  
Western Interior Seaway

The fossil record of centrosaurine ceratopsids is largely restricted to the northern region of western North America (Alberta, Montana and Alaska). Exceptions consist of single taxa from Utah ( Diabloceratops ) and China ( Sinoceratops ), plus otherwise fragmentary remains from the southern Western Interior of North America. Here, we describe a remarkable new taxon, Nasutoceratops titusi n. gen. et sp., from the late Campanian Kaiparowits Formation of Utah, represented by multiple specimens, including a nearly complete skull and partial postcranial skeleton. Autapomorphies include an enlarged narial region, pneumatic nasal ornamentation, abbreviated snout and elongate, rostrolaterally directed supraorbital horncores. The subrectangular parietosquamosal frill is relatively unadorned and broadest in the mid-region. A phylogenetic analysis indicates that Nasutoceratops is the sister taxon to Avaceratops , and that a previously unknown subclade of centrosaurines branched off early in the group's history and persisted for several million years during the late Campanian. As the first well-represented southern centrosaurine comparable in age to the bulk of northern forms, Nasutoceratops provides strong support for the provincialism hypothesis, which posits that Laramidia—the western landmass formed by inundation of the central region of North America by the Western Interior Seaway—hosted at least two coeval dinosaur communities for over a million years of late Campanian time.

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