scholarly journals Morphological variation in Naomichelys (Testudinata: Solemydidae): insights from a new specimen from the Lower Cretaceous Cloverly Formation of Montana

2015 ◽  
Author(s):  
Daniel Lawver
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Lower Cretaceous ◽  
Cervical Vertebrae ◽  
Shoulder Girdle ◽  
Distinct Species ◽  
Upper Jurassic ◽  
Holotype Specimen ◽  
Surface Ornamentation ◽  
The Right

Background. Solemydidae is an enigmatic clade of stem turtles, which is primarily represented by fragmentary shell material found in Upper Jurassic and Cretaceous deposits of Europe and North America. Specimens are typically identified by a distinct surface ornamentation comprised of tall, narrow tubercles, which are often incompletely preserved due to taphonomic processes. The only currently recognized North American species of Solemydidae, Naomichelys speciosa was erected in 1908 on the basis of a nearly complete entoplastron from the Lower Cretaceous Cloverly Formation of Montana; however, a far more complete specimen from the Lower Cretaceous Antler Formation of Texas (FMNH PR273) was recently referred to this species and has shed light on the morphology of Naomichelys. Here, I describe a partial skeleton (MOR 941) that was discovered in 1995 near the type locality in Montana, which allows for the first look at variation in many of the skeletal elements of the genus. Methods. Morphological variation of Naomichelys was determined by comparison of MOR 941 to the holotype specimen and FMNH PR273 from the literature. Results. MOR 941 is referable to Solemydidae based on a large, diamond shaped entoplastron, which exhibits the distinctive solemydid surface ornamentation and an entoplastral scute, and is referable to Naomichelys because of its near identical morphology to that of the holotype. This specimen consists of the carapace, plastron, four cervical vertebrae, both shoulder girdles, and the right femur. Preserved carapacial elements are the right costals and peripherals in articulation, albeit somewhat crushed, disarticulated left costals, and a single neural. Using peripheral and costal sutures as well as marginal sulci as landmarks, peripherals 1 – 4 are identified, which indicates that the nuchal notch is either reduced or lacking completely. The plastron is well preserved with only portions of the left bridge and xiphiplastra missing and a central plastral fontanel is completely lacking. Cervical vertebrae 5 – 8 are preserved and show varying states of completeness with C7 being the most complete. Cervical 5 preserves a ventral keel on the centrum that is well developed and projects well beyond the central articulations. The shoulder girdle elements are similar to FMNH PR273 but are less well preserved and are not sutured together. The femur is complete and almost identical to FMNH PR273; however, the distal condyles are equally developed. Discussion. The morphological differences between MOR 941 and the Texas material suggest two plausible conclusions. 1) They demonstrate two different ontogenetic stages of development, with MOR 941 representing a skeletally more mature, albeit smaller individual; or 2) there are two distinct species of Naomichelys from the Lower Cretaceous of North America.

scholarly journals Morphological variation in Naomichelys (Testudinata: Solemydidae): insights from a new specimen from the Lower Cretaceous Cloverly Formation of Montana

2015 ◽  
Author(s):  
Daniel Lawver
Keyword(s):  
North America ◽  
Morphological Variation ◽  
Lower Cretaceous ◽  
Cervical Vertebrae ◽  
Shoulder Girdle ◽  
Distinct Species ◽  
Upper Jurassic ◽  
Holotype Specimen ◽  
Surface Ornamentation ◽  
The Right

Background. Solemydidae is an enigmatic clade of stem turtles, which is primarily represented by fragmentary shell material found in Upper Jurassic and Cretaceous deposits of Europe and North America. Specimens are typically identified by a distinct surface ornamentation comprised of tall, narrow tubercles, which are often incompletely preserved due to taphonomic processes. The only currently recognized North American species of Solemydidae, Naomichelys speciosa was erected in 1908 on the basis of a nearly complete entoplastron from the Lower Cretaceous Cloverly Formation of Montana; however, a far more complete specimen from the Lower Cretaceous Antler Formation of Texas (FMNH PR273) was recently referred to this species and has shed light on the morphology of Naomichelys. Here, I describe a partial skeleton (MOR 941) that was discovered in 1995 near the type locality in Montana, which allows for the first look at variation in many of the skeletal elements of the genus. Methods. Morphological variation of Naomichelys was determined by comparison of MOR 941 to the holotype specimen and FMNH PR273 from the literature. Results. MOR 941 is referable to Solemydidae based on a large, diamond shaped entoplastron, which exhibits the distinctive solemydid surface ornamentation and an entoplastral scute, and is referable to Naomichelys because of its near identical morphology to that of the holotype. This specimen consists of the carapace, plastron, four cervical vertebrae, both shoulder girdles, and the right femur. Preserved carapacial elements are the right costals and peripherals in articulation, albeit somewhat crushed, disarticulated left costals, and a single neural. Using peripheral and costal sutures as well as marginal sulci as landmarks, peripherals 1 – 4 are identified, which indicates that the nuchal notch is either reduced or lacking completely. The plastron is well preserved with only portions of the left bridge and xiphiplastra missing and a central plastral fontanel is completely lacking. Cervical vertebrae 5 – 8 are preserved and show varying states of completeness with C7 being the most complete. Cervical 5 preserves a ventral keel on the centrum that is well developed and projects well beyond the central articulations. The shoulder girdle elements are similar to FMNH PR273 but are less well preserved and are not sutured together. The femur is complete and almost identical to FMNH PR273; however, the distal condyles are equally developed. Discussion. The morphological differences between MOR 941 and the Texas material suggest two plausible conclusions. 1) They demonstrate two different ontogenetic stages of development, with MOR 941 representing a skeletally more mature, albeit smaller individual; or 2) there are two distinct species of Naomichelys from the Lower Cretaceous of North America.

A review of the Late Jurassic stegosaurs (Dinosauria, Stegosauria) from the People's Republic of China

2006 ◽  
Vol 143 (5) ◽  
pp. 621-634 ◽  
Author(s):  
SUSANNAH C. R. MAIDMENT ◽  
GUANGBIAO WEI
Keyword(s):  
North America ◽  
Late Jurassic ◽  
Taxonomic Revision ◽  
Upper Jurassic ◽  
Supplementary Data ◽  
Asian Origin ◽  
Republic Of China ◽  
Holotype Specimen ◽  
The World ◽  
Cladistic Analyses

Seven genera of stegosaurian dinosaur have been named on the basis of material from the Upper Jurassic of China, and this represents a diversity of stegosaurs unparalleled around the world at this time. However, many of the original specimens used to diagnose and describe these species are currently unavailable, and the original descriptions and figures are often inadequate. The Chinese stegosaurs have proven ‘unstable’ in the few cladistic analyses of Stegosauria that have been carried out, causing a loss of resolution in cladograms. Supplementary data on previously described specimens are presented here along with a taxonomic revision. Only Tuojiangosaurus multispinus, Chungkingosaurus jiangbeiensis and Gigantspinosaurus sichuanensis are considered to be valid taxa, with autapomorphies pertaining to features of the ilio-sacral blocks and dermal armour in all cases. The holotype specimen of ‘Chialingosaurus kuani’ is a juvenile, bearing no diagnostic characters, and ‘Monkonosaurus lawulacus’ is based on fragmentary and undiagnostic material. ‘Changtusaurus’ and ‘Yingshanosaurus’ have never been described or figured and their whereabouts are unknown, so they are regarded as nomina nuda. This taxonomic revision significantly reduces known stegosaurian diversity worldwide, and shows that the Chinese diversity was similar to that of Europe and North America in the Upper Jurassic. Previously, it had been suggested that the diversity of Chinese stegosaurs indicated an Asian origin for the clade, a claim that cannot now be upheld.

scholarly journals Osteology ofGaleamopus pabstisp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3179 ◽  
Author(s):  
Emanuel Tschopp ◽  
Octávio Mateus
Keyword(s):  
Cervical Vertebrae ◽  
Niche Partitioning ◽  
Type Specimen ◽  
Upper Jurassic ◽  
Body Parts ◽  
Morrison Formation ◽  
Dorsal Vertebra ◽  
Important Indicator ◽  
Horizontal Canal ◽  
Holotype Specimen

Diplodocids are among the best known sauropod dinosaurs. Numerous specimens of currently 15 accepted species belonging to ten genera have been reported from the Late Jurassic to Early Cretaceous of North and South America, Europe, and Africa. The highest diversity is known from the Upper Jurassic Morrison Formation of the western United States: a recent review recognized 12 valid, named species, and possibly three additional, yet unnamed ones. One of these is herein described in detail and referred to the genusGaleamopus. The holotype specimen ofGaleamopus pabstisp. nov., SMA 0011, is represented by material from all body parts but the tail, and was found at the Howe-Scott Quarry in the northern Bighorn Basin in Wyoming, USA. Autapomorphic features of the new species include a horizontal canal on the maxilla that connects the posterior margin of the preantorbital and the ventral margin of the antorbital fenestrae, a vertical midline groove marking the sagittal nuchal crest, the presence of a large foramen connecting the postzygapophyseal centrodiapophyseal fossa and the spinopostzygapophyseal fossa of mid- and posterior cervical vertebrae, a very robust humerus, a laterally placed, rugose tubercle on the concave proximal portion of the anterior surface of the humerus, a relatively stout radius, the absence of a distinct ambiens process on the pubis, and a distinctly concave posteroventral margin of the ascending process of the astragalus. In addition to the holotype specimen SMA 0011, the skull USNM 2673 can also be referred toGaleamopus pabsti. Histology shows that the type specimen SMA 0011 is sexually mature, although neurocentral closure was not completed at the time of death. Because SMA 0011 has highly pneumatized cervical vertebrae, the development of the lamination appears a more important indicator for individual age than neurocentral fusion patterns. SMA 0011 is one of very few sauropod specimens that preserves the cervico-dorsal transition in both vertebrae and ribs. The association of ribs with their respective vertebrae shows that the transition between cervical and dorsal vertebrae is significantly different inGaleamopus pabstithan inDiplodocus carnegiiorApatosaurus louisae, being represented by a considerable shortening of the centra from the last cervical to the first dorsal vertebra. Diplodocids show a surprisingly high diversity in the Morrison Formation. This can possibly be explained by a combination of geographical and temporal segregation, and niche partitioning.

scholarly journals Quaternary proboscidean (Mammalia) remains of the UIS Geological Museum, Colombia

2021 ◽  
Vol 24 (1) ◽  
pp. 70-75
Author(s):  
Jaime Yesid Suárez-Ibarra ◽  
Gina Cardoso ◽  
Lidiane Asevedo ◽  
Lucas de Melo França ◽  
Mário André Trindade Dantas ◽  
...  
Keyword(s):  
Older Adults ◽  
North America ◽  
South America ◽  
Distal Part ◽  
Cervical Vertebrae ◽  
The Other ◽  
Fossil Remains ◽  
Geological Museum ◽  
Great American Biotic Interchange ◽  
The Right

Proboscideans arrived in South America from North America during the Great American Biotic Interchange, becoming one of the most representative animals of the megafauna that inhabited this continent throughout the Quaternary. In Colombia, the abundance of their remains contrasts with scarce scientific descriptions and publications. This paper identifies dental and postcranial proboscidean fossils from the Center and Northeast of Colombia. The fossil remains were identified as molars (six), a tusk, cervical vertebrae, and a distal part of the right humerus. The tusk was assigned to Notiomastodon platensis, while the other remains were assigned to Gomphotheriidae, with at least six individuals: two immatures, two subadults, and two older adults – mature and senile. Keywords: South America, megamammals, taxonomy, Gomphotheriidae, Notiomastodon platensis.

Multiple subluxations and comminuted fracture of the cervical spine in a sheep

2015 ◽  
Vol 43 (01) ◽  
pp. 44-38
Author(s):  
C.-C. Lin ◽  
K.-S. Chen ◽  
Y.-L. Lin ◽  
J. P.-W. Chan
Keyword(s):  
Cervical Spine ◽  
Pain Perception ◽  
Cervical Vertebrae ◽  
Traumatic Injury ◽  
Spinal Reflexes ◽  
Spine Trauma ◽  
Blunt Force Trauma ◽  
Comminuted Fracture ◽  
History Of ◽  
The Right

SummaryA 5-month-old, 13.5 kg, female Corriedale sheep was referred to the Veterinary Medicine Teaching Hospital, with a history of traumatic injury of the cervical spine followed by non-ambulatoric tetraparesis that occurred 2 weeks before being admitted to the hospital. At admission, malalignment of the cervical spine with the cranial part of the neck deviating to the right was noted. Neurological examinations identified the absence of postural reactions in both forelimbs, mildly decreased spinal reflexes, and normal reaction to pain perception tests. Radiography revealed malalignment of the cervical vertebrae with subluxations at C1–C2 and C2–C3, and a comminuted fracture of the caudal aspect of C2. The sheep was euthanized due to a presumed poor prognosis. Necropsy and histopathological findings confirmed injuries of the cervical spine from C1 to C3, which were consistent with the clinical finding of tetraparesis in this case. This paper presents a rare case of multiple subluxations of the cervical spine caused by blunt force trauma in a young sheep. These results highlight the importance of an astute clinical diagnosis for such an acute cervical spine trauma and the need for prompt surgical correction for similar cases in the future.

First Mesozoic representative of the subfamily Liparochrinae (Coleoptera: Hybosoridae) from the Lower Cretaceous Lebanese amber

2011 ◽  
Vol 20 (1) ◽  
pp. 62-70
Author(s):  
A.G. Kirejtshuk ◽  
D. Azar ◽  
O. Montreuil
Keyword(s):  
Lower Cretaceous ◽  
Median Part ◽  
The Right

One specimen among coleopterous inclusions recently recovered in Lebanese amber is described as Libanochrus calvus gen. et sp. nov. and assigned to the subfamily Liparochrinae of the Hybosoridae. This specimen is incomplete but a large part of its head with appendages, prothoracic segment with anterior legs, remains of the median part of the pterothoracic underside and the lateral base of the of the right elytron make possible the conclusion on the subfamily attribution and diagnose it among the rest of fossil and recent taxa of this family. At present it is the oldest representative of the subfamily.

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