Gondwanatheria and ?Multituberculata (Mammalia) from the Late Cretaceous of Madagascar

2013 ◽  
Vol 50 (3) ◽  
pp. 324-340 ◽  
Author(s):  
David W. Krause
Keyword(s):  
Late Cretaceous ◽  
New Taxon ◽  
Negative Evidence ◽  
Mammalian Fauna ◽  
Micro Computed Tomography ◽  
Lower Incisor ◽  
Computed Tomography Scans ◽  
Size Variability ◽  
Mammalian Teeth ◽  
Insight Into

In addition to four isolated mammalian teeth from the Late Cretaceous (Maastrichtian) of Madagascar described previously and allocated to Gondwanatheria, Marsupialia, and Mammalia incertae sedis, here I put on record five more specimens. Four of these, a virtually complete lower molariform cheek tooth, two fragmentary cheek teeth, and a fragmentary lower incisor, are referred to the Sudamericidae (Gondwanatheria). The internal structure of the hypsodont cheek teeth, as revealed by micro-computed tomography scans to simulate different stages of wear, is highly variable. Limited knowledge of intra-individual morphological and size variability in the dentition of sudamericids, which are known almost exclusively from isolated teeth, precludes a conclusive assessment of whether some or all of the new specimens belong to Lavanify miolaka, the only previously described sudamericid from Madagascar, or to a new taxon. Conservatively, therefore, pending the recovery of better material, all four specimens are referred to Sudamericidae gen. et sp. indet. The fifth specimen, a molar fragment, is tentatively allocated to the Multituberculata, thereby adding to the controversial specimens that comprise the very sparse and questionable record of this clade on the southern supercontinent Gondwana. The new specimens do not provide any profound insight into the origins of the highly endemic and imbalanced extant mammalian fauna on Madagascar; rather, they provide only more negative evidence. Like those previously described, they do not represent the basal stocks of any of the five mammalian clades that live on the island today and therefore further support the growing consensus that representatives of the extant clades arrived in the Cenozoic.

scholarly journals A new fossil dolphin Dilophodelphis fordycei provides insight into the evolution of supraorbital crests in Platanistoidea (Mammalia, Cetacea)

2017 ◽  
Vol 4 (5) ◽  
pp. 170022 ◽  
Author(s):  
Alexandra T. Boersma ◽  
Matthew R. McCurry ◽  
Nicholas D. Pyenson
Keyword(s):  
South Asian ◽  
Middle Miocene ◽  
Sound Propagation ◽  
Early Miocene ◽  
New Taxon ◽  
Internal Morphology ◽  
Computed Tomography Scans ◽  
Evolutionary Context ◽  
And Function ◽  
Insight Into

Many odontocete groups have developed enlarged facial crests, although these crests differ in topography, composition and function. The most elaborate crests occur in the South Asian river dolphin ( Platanista gangetica ), in which they rise dorsally as delicate, pneumatized wings anterior of the facial bones. Their position wrapping around the melon suggests their involvement in sound propagation for echolocation. To better understand the origin of crests in this lineage, we examined facial crests among fossil and living Platanistoidea, including a new taxon, Dilophodelphis fordycei , nov. gen. and sp., described herein, from the Early Miocene Astoria Formation of Oregon, USA. We measured the physical extent and thickness of platanistoid crests, categorized their relative position and used computed tomography scans to examine their internal morphology and relative bone density. Integrating these traits in a phylogenetic context, we determined that the onset of crest elaboration or enlargement and the evolution of crest pneumatization among the platanistoids were separate events, with crest enlargement beginning in the Oligocene. However, we find no evidence for pneumatization until possibly the Early Miocene, although certainly by the Middle Miocene. Such an evolutionary context, including data from the fossil record, should inform modelling efforts that seek to understand the diversity of sound generation morphology in Odontoceti.

A new species of Sclerocephalus with a fully ossified endocranium gives insight into braincase evolution in temnospondyls

2021 ◽  
pp. 1-13
Author(s):  
Rainer R. Schoch ◽  
Gabriela Sobral
Keyword(s):  
New Species ◽  
Character Evolution ◽  
Late Paleozoic ◽  
New Taxon ◽  
Early Permian ◽  
Top Predator ◽  
Central European ◽  
Wide Range ◽  
A New Species ◽  
Insight Into

Abstract The late Paleozoic temnospondyl Sclerocephalus formed an aquatic top predator in various central European lakes of the late Carboniferous and early Permian. Despite hundreds of specimens spanning a wide range of sizes, knowledge of the endocranium (braincase and palatoquadrate) remained very insufficient in Sclerocephalus and other stereospondylomorphs because even large skulls had unossified endocrania. A new specimen from a stratigraphically ancient deposit at St. Wendel in southwestern Germany is recognized as representing a new taxon, S. concordiae new species, and reveals a completely ossified endocranium. The sphenethmoid was completely ossified from the basisphenoid to the anterior ethmoid region, co-ossified with the parasphenoid, and the basipterygoid joint was fully established. The pterygoid bears a slender, S-shaped epipterygoid, which formed a robust pillar lateral to the braincase. The massive stapes was firmly sutured to the parasphenoid. In the temnospondyl endocranium, character evolution involved various changes in the epipterygoid region, which evolved distinct morphologies in each of the major clades. UUID: http://zoobank.org/5e6d2078-eacf-4467-84cf-a12efcae7c0b

scholarly journals An early bothremydid (Testudines, Pleurodira) from the Late Cretaceous (Cenomanian) of Utah, North America

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2502 ◽  
Author(s):  
Walter G. Joyce ◽  
Tyler R. Lyson ◽  
James I. Kirkland
Keyword(s):  
Phylogenetic Analysis ◽  
Late Cretaceous ◽  
New Taxon ◽  
The Novel ◽  
Depositional Settings ◽  
Near Shore ◽  
Phylogenetic Hypotheses ◽  
North And South America ◽  
North And South ◽  
Early Late

BackgroundBothremydidae is a clade of extinct pleurodiran turtles known from the Cretaceous to Paleogene of Africa, Europe, India, Madagascar, and North and South America. The group is most diverse during the Late Cretaceous to Paleogene of Africa. Little is known, however, about the early evolution of the group.MethodsWe here figure and describe a fossil turtle from early Late Cretaceous deposits exposed at MacFarlane Mine in Cedar Canyon, southwestern Utah, USA. The sediments associated with the new turtle are utilized to infer its stratigraphic provenience and the depositional settings in which it was deposited. The fossil is compared to previously described fossil pleurodires, integrated into a modified phylogenetic analysis of pelomedusoid turtles, and the biogeography of bothremydid turtles is reassessed. In light of the novel phylogenetic hypotheses, six previously established taxon names are converted to phylogenetically defined clade names to aid communication.ResultsThe new fossil turtle can be inferred with confidence to have originated from a brackish water facies within the late Cenomanian Culver Coal Zone of the Naturita Formation. The fossil can be distinguished from all other previously described pleurodires and is therefore designated as a new taxon,Paiutemys tibertgen. et. sp. nov. Phylogenetic analysis places the new taxon as sister to the EuropeanPolysternon provinciale,Foxemys trabantiandFoxemys mechinorumat the base of Bothremydinae. Biogeographic analysis suggests that bothremydids originated as continental turtles in Gondwana, but that bothremydines adapted to near-shore marine conditions and therefore should be seen as having a circum-Atlantic distribution.

scholarly journals A redescription of the Late Jurassic (Tithonian) turtle Uluops uluops and a new phylogenetic hypothesis of Paracryptodira

2021 ◽  
Vol 140 (1) ◽  
Author(s):  
Yann Rollot ◽  
Serjoscha W. Evers ◽  
Walter G. Joyce
Keyword(s):  
Computed Tomography ◽  
Phylogenetic Analysis ◽  
Late Jurassic ◽  
Internal Carotid ◽  
Circulation System ◽  
Phylogenetic Hypothesis ◽  
Micro Computed Tomography ◽  
Future Studies ◽  
Computed Tomography Scans ◽  
Palatine Artery

AbstractWe study the Late Jurassic (Tithonian) turtle Uluops uluops using micro-computed tomography scans to investigate the cranial anatomy of paracryptodires, and provide new insights into the evolution of the internal carotid artery and facial nerve systems, as well as the phylogenetic relationships of this group. We demonstrate the presence of a canalis caroticus lateralis in Uluops uluops, the only pleurosternid for which a palatine artery canal can be confidently identified. Our phylogenetic analysis retrieves Uluops uluops as the earliest branching pleurosternid, Helochelydridae within Pleurosternidae, and Compsemydidae including Kallokibotion bajazidi within Baenidae, which suggests at least two independent losses of the palatine artery within paracryptodires. We expect future studies will provide additional insights into the evolution of the circulation system of paracryptodires, as well as clarifying relationships along the turtle stem.

Changing minds about climate change: a pervasive role for domain-general metacognition

2021 ◽  
Author(s):  
Manos Tsakiris ◽  
Neza Vehar ◽  
Stephen M Fleming ◽  
Sophie De Beukelaer ◽  
Max Rollwage
Keyword(s):  
Climate Change ◽  
Climate Science ◽  
Social Effects ◽  
Negative Evidence ◽  
Prior Beliefs ◽  
Domain Specific ◽  
The Face ◽  
Metacognitive Abilities ◽  
Insight Into

Updating one’s beliefs about the causes and effects of climate change is crucial for altering attitudes and behaviours. Importantly, metacognitive abilities - insight into the (in)correctness of one’s beliefs- play a key role in the formation of polarized beliefs. We investigated the role of domain-general and domain-specific metacognition in updating prior beliefs about climate change across the spectrum of climate change scepticism. We also considered the role of how climate science is communicated in the form of textual or visuo-textual presentations. We show that climate change scepticism is associated with differences in domain-general as well as domain-specific metacognitive abilities. Moreover, domain-general metacognitive sensitivity influenced belief updating in an asymmetric way : lower domain-general metacognition decreased the updating of prior beliefs, especially in the face of negative evidence. Our findings highlight the role of metacognitive failures in revising erroneous beliefs about climate change and point to their adverse social effects.

Ichthyosaurs from the Upper Triassic (Carnian–Norian) of the New Siberian Islands, Russian Arctic, and their implications for the evolution of the ichthyosaurian basicranium and vertebral column

2021 ◽  
pp. 1-24
Author(s):  
Nikolay G. ZVERKOV ◽  
Dmitry V. GRIGORIEV ◽  
Andrzej S. WOLNIEWICZ ◽  
Alexey G. KONSTANTINOV ◽  
Evgeny S. SOBOLEV
Keyword(s):  
Vertebral Column ◽  
Cervical Vertebrae ◽  
Upper Triassic ◽  
Late Triassic ◽  
Phylogenetic Position ◽  
New Taxon ◽  
Russian Arctic ◽  
Micro Computed Tomography ◽  
New Siberian Islands ◽  
Group Relationships

ABSTRACT The first ichthyosaurian specimens discovered from the Upper Triassic of the Russian Arctic (Kotelny Island, New Siberian Islands) are described herein. They include the remains of large- to small-bodied ichthyosaurians originating from six stratigraphic levels spanning the lower Carnian to middle Norian. The material is mostly represented by isolated vertebrae and ribs, which are not possible to accurately diagnose, but also includes specimens comprising associated vertebrae and a fragmentary skeleton that preserves cranial remains (parabasisphenoid, fragmentary quadrate, partial mandible and hyoids). Based on vertebral and rib morphology, we identify the specimens as representatives of the following taxonomic groups: large-bodied shastasaurids, medium-sized indeterminate ichthyosaurians with a single rib facet in the presacral centra, and small euichthyosaurians with double rib facets present throughout the presacral vertebrae that likely represent toretocnemids and/or basal parvipelvians. In addition, the cranial and mandibular remains preserved in one of the specimens, ZIN PH 5/250, were studied using micro-computed tomography. Its mandible is highly similar to that of toretocnemids, whereas the parabasisphenoid demonstrates a peculiar combination of both plesiomorphic and derived character states, providing the first detailed data on this cranial element in a Late Triassic ichthyosaurian. Furthermore, the specimen also demonstrates a distinctive condition of rib articulation in the anteriormost presacral (cervical) vertebrae, which together with other features allows for the erection of a new taxon – Auroroborealia incognita gen. et sp. nov. Although the phylogenetic position of this taxon is uncertain due to its fragmentary nature, its anatomy, indicating toretocnemid or parvipelvian affinities, further supports the previously hypothesised sister-group relationships between these two clades. The morphology of the parabasisphenoid and vertebral column of the new taxon is discussed in broader contexts of the patterns of evolution of these skeletal regions in ichthyosaurs.

scholarly journals How pigeons couple three-dimensional elbow and wrist motion to morph their wings

2017 ◽  
Vol 14 (133) ◽  
pp. 20170224 ◽  
Author(s):  
Amanda K. Stowers ◽  
Laura Y. Matloff ◽  
David Lentink
Keyword(s):  
Three Dimensional ◽  
Columba Livia ◽  
Micro Computed Tomography ◽  
Wrist Motion ◽  
Motion Data ◽  
Morphing Wings ◽  
Computed Tomography Scans ◽  
Motion Paths ◽  
Wing Morphing ◽  
Planar Drawing

Birds change the shape and area of their wings to an exceptional degree, surpassing insects, bats and aircraft in their ability to morph their wings for a variety of tasks. This morphing is governed by a musculoskeletal system, which couples elbow and wrist motion. Since the discovery of this effect in 1839, the planar ‘drawing parallels’ mechanism has been used to explain the coupling. Remarkably, this mechanism has never been corroborated from quantitative motion data. Therefore, we measured how the wing skeleton of a pigeon ( Columba livia ) moves during morphing. Despite earlier planar assumptions, we found that the skeletal motion paths are highly three-dimensional and do not lie in the anatomical plane, ruling out the ‘drawing parallels’ mechanism. Furthermore, micro-computed tomography scans in seven consecutive poses show how the two wrist bones contribute to morphing, particularly the sliding ulnare. From these data, we infer the joint types for all six bones that form the wing morphing mechanism and corroborate the most parsimonious mechanism based on least-squares error minimization. Remarkably, the algorithm shows that all optimal four-bar mechanisms either lock, are unable to track the highly three-dimensional bone motion paths, or require the radius and ulna to cross for accuracy, which is anatomically unrealistic. In contrast, the algorithm finds that a six-bar mechanism recreates the measured motion accurately with a parallel radius and ulna and a sliding ulnare. This revises our mechanistic understanding of how birds morph their wings, and offers quantitative inspiration for engineering morphing wings.

scholarly journals New turtle remains from the Late Cretaceous of Monte Alto-SP, Brazil, including cranial osteology, neuroanatomy and phylogenetic position of a new taxon

PalZ ◽  
2018 ◽  
Vol 92 (3) ◽  
pp. 481-498 ◽  
Author(s):  
Gabriel S. Ferreira ◽  
Fabiano V. Iori ◽  
Guilherme Hermanson ◽  
Max C. Langer
Keyword(s):  
Late Cretaceous ◽  
Phylogenetic Position ◽  
New Taxon ◽  
Cranial Osteology

scholarly journals A new dromaeosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Wulansuhai Formation of Inner Mongolia, China

Zootaxa ◽  
2010 ◽  
Vol 2403 (1) ◽  
pp. 1 ◽  
Author(s):  
XING XU ◽  
JONAH N. CHOINIERE ◽  
MICHAEL PITTMAN ◽  
QINGWEI TAN ◽  
DONG XIAO ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Inner Mongolia ◽  
Upper Cretaceous ◽  
Systematic Position ◽  
Sister Taxon ◽  
New Taxon ◽  
Salient Features

We describe a new dromaeosaurid theropod from the Upper Cretaceous Wulansuhai Formation of Bayan Mandahu, Inner Mongolia. The new taxon, Linheraptor exquisitus gen. et sp. nov., is based on an exceptionally well-preserved, nearly complete skeleton. This specimen represents the fifth dromaeosaurid taxon recovered from the Upper Cretaceous Djadokhta Formation and its laterally equivalent strata, which include the Wulansuhai Formation, and adds to the known diversity of Late Cretaceous dromaeosaurids. Linheraptor exquisitus closely resembles the recently reported Tsaagan mangas. Uniquely among dromaeosaurids, the two taxa share a large, anteriorly located maxillary fenestra and a contact between the jugal and the squamosal that excludes the postorbital from the infratemporal fenestra. These features suggest a sister-taxon relationship between L. exquisitus and T. mangas, which indicates the presence of a unique dromaeosaurid lineage in the Late Cretaceous of Asia. A number of cranial and dental features seen in L. exquisitus and T. mangas, and particularly some postcranial features of L. exquisitus, suggest that these two taxa are probably intermediate in systematic position between known basal and derived dromaeosaurids. The discovery of Linheraptor exquisitus is thus important for understanding the evolution of some salient features seen in the derived dromaeosaurids.

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