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New Upper Jurassic marine vertebrates from a bonebed in the Atacama Desert, northern Chile

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Published by Libros digitales, 2019-08-05 11:43:26

New Upper Jurassic marine vertebrates from a bonebed in the Atacama Desert, northern Chile

New Upper Jurassic marine vertebrates from a bonebed in the Atacama Desert, northern Chile

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More than 3000 living species of snakes share a limbless body plan, and are adapted vertebral column, part of the rib cage, the right scapula and partial right forelimb, part of
to varying media including air (flying snakes), soil (burrowing snakes) and water (sea the pelvic girdle and parts of both hind limbs, the right hind limb being almost complete.
snakes). It is hotly debated whether snakes developed their specialized locomotion in a It is distinguished from other coelophysoid theropods by the unique combination of the
terrestrial or aquatic environment. This study uses endocranial structures (ossified inner following six character states: 1) large internal antorbital fenestra, 2) diagonal
ear) of recent and fossil snakes to test the hypotheses: 1) inner-ear morphology is (rostrodorsal-caudoventral) ridge on lateral surface of maxilla, within antorbital fossa, 3)
indicative of snake locomotion styles including fossorial, surface active or aquatic; 2) the elliptical, laterally facing fenestra caudodorsal to aforementioned diagonal ridge, 4)
inner ear of Dinilysia patagonica, one of the oldest fossil snakes, suggests it to be a presence of promaxillary fenestra, 5) long maxillary body, and 6) hooked craniomedial
burrower. To test the hypotheses, 10 snake species and 9 lizard species are CT-scanned corner of distal tarsal IV. Cladistic analysis recovers (LFGZ) ZLJ0103 as a member of a
for inner-ear morphology. The sampling covers all major clades of snakes, and includes clade that also includes 'Syntarsus' and Coelophysis, and indicates that (LFGZ) ZLJ0103
both limbed and limbless lizard species for outgroup comparisons. The ossified inner ear is more closely related to Coelophysis than to 'Syntarsus'. (LFGZ) ZLJ0103 represents the
is segmented and reconstructed three-dimensionally, including three semicircular canals first well-preserved coelophysoid theropod dinosaur from Asia, and provides fresh
(anterior, posterior, and lateral) and the vestibule that form the vestibular (balance) evidence supporting the hypothesis that terrestrial tetrapods tended to be distributed pan-
apparatus of all vertebrates. The results show that distance between the lateral continentally during the Early Jurassic.
semicircular canal (SCC) and vestibule is indicative of locomotion in snakes. Among the
three locomotion categories sampled, fossorial species show a highly reduced lateral SCC Poster Session IV (Saturday, November 2, 2013, 4:15 - 6:15 PM)
that is partly fused with the vestibule. In contrast, aquatic species, represented by several
species of sea snakes, show an expanded distance between lateral SCC and the vestibule. NEW UPPER JURASSIC MARINE VERTEBRATES FROM A BONEBED IN
Non-burrowing terrestrial snakes show an intermediate state where the lateral SCC does THE ATACAMA DESERT, NORTHERN CHILE
not fuse with the vestibule, but is not as expanded as in sea snakes. Results in extant
species provides a context for comparison for the fossil snake Dinilysia patagonica. YURY-YÁÑEZ, Roberto, Red Paleontológica Universidad de Chile, Santiago de Chile,
Recently published CT images of Dinilysia patagonica shows that its lateral SCC is Chile; SOTO-ACUÑA, Sergio, Red Paleontológica Universidad de Chile, Santiago de
slender and nearly fused to the vestibule, resembling the fossorial Asian sunbeam snakes Chile, Chile; OTERO, Rodrigo, Red Paleontológica Universidad de Chile, Santiago de
(Xenopeltis unicolor). Our observations in extant snakes suggest that this resemblance is Chile, Chile; ROJAS, Osvaldo, Museo de Historia Natural y Cultural del Desierto de
actually indicative of a burrowing behavior. Since Dinilysia patagonica is a terrestrial Atacama, Calama, Chile; VARGAS, Alexander, Red Paleontológica Universidad de
snake recovered phylogenetically near the root of all snakes, its inner ear provides Chile, Santiago de Chile, Chile
evidence for burrowing behavior for early snakes.
The Upper Jurassic record of marine vertebrates from the Southeastern Pacific is
Poster Session II (Thursday, October 31, 2013, 4:15 - 6:15 PM) restricted to the Callovian-Tithonian of the Neuquén Basin in northwestern Patagonia of
Argentina and the Oxfordian of Northern Chile. Here we provide new information about
NEW SAUROPOD FROM THE CEDAR MOUNTAIN FORMATION OF UTAH, the fossil vertebrate fauna from the Jurassic of Chile. The materials come from a bonebed
USA belonging to the Cerritos Bayos Formation exposed near Calama, Northern Chile, and
were recovered from levels of Oxfordian age. The assemblage is mainly comprised of
YOSHIDA, Junki, Hokkaido University, sapporo, Japan; CARPENTER, Kenneth, Utah abundant bony fishes and reptiles, which are fragmentary but show 3D preservation.
State University Eastern, Price, UT, United States; KOBAYASHI, Yoshitsugu, Hokkaido Reptiles are represented by postcranial material referable to indeterminate cryptocleidian
University Museum, sapporo, Japan plesiosaurs. Also, there is abundant material of thalattosuchian crocodyliforms including
cranial and postcranial remains. Among the firsts is a natural snout endocast of a
The Early Cretaceous Cedar Mountain Formation is known as one of the richest Metriorhynchidae preserving a portion of the rostrum, the nasopharyngeal ducts, the salt
dinosaur bearing formations of the time in North America, and produces the greatest glands and the left orbit. In addition, a large portion of the rostrum as well as part of the
diversity of Early Cretaceous sauropods in North America. Postcranial skeletons of a skull referable to a novel form of ichthyosaur was recovered from the same beds. Finally,
possibly new sauropod dinosaur were discovered from the base of the early Albian we report remains of a new non-pterodactyloid pterosaur represented by a rostral portion
Mussentuchit Member, the uppermost member of the Cedar Mountain Formation, at the of a skull with remarkable heterodonty and a high skull with convex profile. The latter
Price River II (PR2) Quarry near Price, Utah. The PR2 quarry is a multitaxic bonebed comprises the first record of Upper Jurassic pterosaurs in Chile and one of the few
including disarticulated sauropod, ankylosaur (Peloroplites and Cedarpelta), findings of the group in South America during this period. The current study of this
iguanodontian, pterosaur, and turtle materials. The PR2 sauropod specimens include Oxfordian herpetofauna and its comparison with the Jurassic Caribbean and Tethyan
vertebrae (middle cervicals, dorsals, and caudals), forelimbs, and hind limbs, represented reptiles is fundamental to understanding the paleobiogeographic distribution of these
by at least three individuals based on the number of metacarpals. Phylogenetic analysis reptilian lineages. The faunas previously described in the Jurassic of the Neuquén Basin
demonstrates that five synapomorphies of Titanosauriformes are present in the PR2 shows close relationships with the Western Tethyan faunas in Europe, supporting the
sauropod: camellate internal structure of the presacral vertebrae, anterior position of the Caribbean Seaway as a migration route used by marine reptiles.
neural arch on the centrum of anterior and middle caudal vertebrae, metacarpal I with
undivided distal condyles, ratio of the haemal canal height and total chevron height Technical Session VI (Thursday, October 31, 2013, 10:45 AM)
approximately 0.5 in anterior caudal vertabrae, and pubic peduncle of ilium 1.5 times
wider than long anteroposteriorly. The PR2 sauropod forms an unresolved polytomy with A REASSESSMENT OF THE MONOPHYLY OF CARNIVORAMORPHA
the Early Cretaceous derived brachiosaurids from the Ceder Mountain Formation (MAMMALIA)
(Abydosaurus from the Albian Mussentuchit Member, Cedarosaurus from the Barremian
Yellow Cat Member, and Venenosaurus from the Aptian-Albian Poison Strip Member), ZACK, Shawn, University of Arizona College of Medicine-Phoenix, Phoenix, AZ,
sharing a synapomorphy (reduced fourth trochanter of the femur). This sauropod is United States, 85004
probably a new taxon because it shows unique combination of characters (high iliac
peduncle of ischium, vertically to posterodorsally projecting neural spines of middle Carnivoramorpha, including crown group Carnivora and the Paleocene-Eocene
caudal vertebrae, and gracile humerus, absence of transverse process with deep fossa into families Miacidae and Viverravidae, is widely acknowledged to be monophyletic and has
ventral face), differing from the other derived brachiosaurids. The occurrence of four historically been characterized by a suite of dental synapomorphies. Most notably,
derived brachiosaurids in the Cedar Mountain Formation indicates a great diversity of restriction of carnassial shear to the P4/m1 pair is widely recognized as a distinctive
brachiosaurids in Utah during the Early Cretaceous, and suggests an actual time range for feature that distinguishes carnivoramorphans from other carnivorous eutherians,
the existence of the derived brachiosaurids in this region between the Barremian and including the likely non-monophyletic order Creodonta. Previous tests of
Albian. carnivoramorphan monophyly have been limited and carnivoramorphan monophyly has
never been tested relative to Oxyaenidae. To remedy this, oxyaenids and additional
Technical Session IX (Friday, November 1, 2013, 8:30 AM) hyaenodontids, as well as several early members of Miacidae and Viverravidae, were
added to a modified version of an existing phylogenetic analysis of carnivoramorphan
A NEW COELOPHYSOID THEROPOD DINOSAUR FROM THE EARLY phylogeny. Neither Creodonta nor Carnivoramorpha was found to be monophyletic.
JURASSIC LUFENG FORMATION OF YUNNAN PROVINCE, CHINA Oxyaenidae was identified as the sister taxon to Carnivoraformes (Miacidae plus
Carnivora), followed by members of Hyaenodontidae. Viverravidae was basal to all other
YOU, Hai-Lu, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese members of the ingroup.
Academy of Sciences, Beijing, China; AZUMA, Yoichi, Fukui Prefectural University,
Fukui, Japan; WANG, Tao, Bureau of Land and Resources of Lufeng County, Lufeng, Three lines of evidence are consistent with non-monophyly of Carnivoramorpha.
China; DONG, Zhi-Ming, Institute of Vertebrate Paleontology and Paleoanthropology, First, some features thought to be synapomorphic for Carnivoramorpha are more broadly
Chinese Academy of Sciences, Beijing, China distributed among early carnivorous eutherians. These include a mesial P4 protocone,
which also occurs in some hyaenodontids and oxyaenids, and distal reduction in molar
Coelophysoid dinosaurs are small- to medium-sized agile bipedal meat-eaters that size, which also occurs in palaeonictine and probably tytthaenine oxyaenids. Second,
lived throughout much of Pangaea during Late Triassic–Early Jurassic time. They are restriction of carnassial shear to the P4/m1 pair appears to be convergent between
among the earliest well-documented dinosaurs and represent the first major radiation of viverravids and miacids, as basal members of both families retain a functional M1/m2
neotheropods. A recent study indicated that late Norian–Rhaetian theropod assemblages carnassial pair (e.g., Simpsonictis, Gracilocyon). Finally, postcranial anatomy supports
were dominated by basal coelophysoids, whereas Early Jurassic ones were composed of monophyly of Oxyaenidae plus Carnivoraformes. Early members of Oxyaenidae and
derived coelophysoids (i.e., the 'Syntarsus' + Coelophysis clade), dilophosaurids and Miacidae show adaptations to relatively mobile limbs, consistent with arboreality or
basal averostrans. However, despite the well-documented discoveries of derived scansoriality. Numerous features of the humerus and tarsus link oxyaenids to miacids to
coelophysoids in North America and Africa, the coelophysoid material that has the exclusion of the more terrestrially adapted hyaenodontids and viverravids.
previously been reported from Asia is limited to two specimens comprising only limb
fragments and perhaps belonging to one individual. Here we report a new coelophysoid © 2013 by the Society of Vertebrate Paleontology
based on a well-preserved skeleton from the same rock unit, the Lower Jurassic Lufeng
Formation of Yunnan Province, China, that yielded both previously reported specimens.
The new specimen, Bureau of Land and Resources of Lufeng County (LFGZ) ZLJ0103,
is represented by an articulated partial skeleton that includes the cranium, the presacral

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