Morphology and orientation of the ichthyosaurian femur

Maxwell, Erin E.; Zammit, Maria; Druckenmiller, Patrick

doi:10.1080/02724634.2012.682834

Cited by 18 publications

(14 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The identity of the femora was determined using the articulated pelvic girdle and hind fin of Cryopterygius [15] and Maxwell et al [47]. The left femur (Figure 12) is better preserved than the right (Figure S2 E-J), but the distal ends of both femora are compressed, so the facets for tibia and fibula are unclear.…”

Section: Resultsmentioning

confidence: 99%

A New Upper Jurassic Ophthalmosaurid Ichthyosaur from the Slottsmøya Member, Agardhfjellet Formation of Central Spitsbergen

et al. 2014

View full text Add to dashboard Cite

Abundant new ichthyosaur material has recently been documented in the Slottsmøya Member of the Agardhfjellet Formation from the Svalbard archipelago of Norway. Here we describe a partial skeleton of a new taxon, Janusaurus lundi, that includes much of the skull and representative portions of the postcranium. The new taxon is diagnosed by a suite of cranial character states including a very gracile stapedial shaft, the presence of a dorsal process on the prearticular and autapomorphic postcranial features such as the presence of an interclavicular trough and a conspicuous anterodorsal process of the ilium. The peculiar morphology of the ilia indicates a previously unrecognized degree of morphological variation in the pelvic girdle of ophthalmosaurids. We also present a large species level phylogenetic analysis of ophthalmosaurids including new and undescribed ichthyosaur material from the Upper Jurassic of Svalbard. Our results recover all Svalbard taxa in a single unresolved polytomy nested within Ophthalmosaurinae, which considerably increases the taxonomic composition of this clade. The paleobiogeographical implications of this result suggest the presence of a single clade of Boreal ophthalmosaurid ichthyosaurs that existed during the latest Jurassic, a pattern also reflected in the high degree of endemicity among some Boreal invertebrates, particularly ammonoids. Recent and ongoing descriptions of marine reptiles from the Slottsmøya Member Lagerstätte provide important new data to test hypotheses of marine amniote faunal turnover at the Jurassic-Cretaceous boundary.

show abstract

Section: Resultsmentioning

confidence: 99%

A New Upper Jurassic Ophthalmosaurid Ichthyosaur from the Slottsmøya Member, Agardhfjellet Formation of Central Spitsbergen

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Option 2 would include three species that are or have been referred to as Platypterygius , including the well‐known Platypterygius australis , for which numerous descriptions and specimens are available (e.g. Wade, ; Wade, ; Kear, ; Zammit, ; Zammit et al ., ; Maxwell, Zammit & Druckenmiller, ); however, we conclude that this option is not advisable, predominantly because it would restrict the name Platypterygius to a clade that probably excludes the current type species, Platypterygius platydactylus , creating even more confusion. Furthermore, the application of the name Platypterygius to this clade would, like option 1, result in an unusual longevity for this taxon (early Barremian–middle Cenomanian, i.e.…”

Section: Discussionmentioning

confidence: 99%

SimbirskiasaurusandPervushovisaurusreassessed: implications for the taxonomy and cranial osteology of Cretaceous platypterygiine ichthyosaurs

et al. 2014

View full text Add to dashboard Cite

The ichthyosaur fossil record is interspersed by several hiatuses, notably during the Cretaceous. This hampers our understanding of the evolution and extinction of this group of marine reptiles during the last 50 million years of its history. Several Cretaceous ichthyosaur taxa named in the past have subsequently been dismissed and referred to the highly inclusive taxon Platypterygius, a trend that has created the impression of low Cretaceous ichthyosaur diversity. Here, we describe the cranial osteology, reassess the stratigraphic age, and evaluate the taxonomy and phylogenetic relationships of two Cretaceous ichthyosaurs from western Russia: Simbirskiasaurus birjukovi from the early Barremian and Pervushovisaurus bannovkensis from the middle Cenomanian, both formerly regarded as nomina dubia, and allocated to Platypterygius sp. and Platypterygius campylodon, respectively. We show that Simbirskiasaurus birjukovi and Pervushovisaurus bannovkensis are valid platypterygiine ophthalmosaurids, notably characterized by a peculiar narial aperture. The cranial anatomy and phylogenetic relationships of these taxa illuminate the evolution of narial aperture anatomy in Cretaceous ichthyosaurs, clarify the phylogenetic relationships among platypterygiines, and provide further arguments for a thorough revision of Platypterygius.

show abstract

“…Compounding the problem are taphonomic biases, given the relatively small size of the pelvic girdle and hind fin and loose nature of their articulation with other pelvic elements and the vertebral column. Thus, these elements are more easily disarticulated from a rotting carcass during floating or disconnected when landing on the sea bottom [ 6 , 14 ]. A similar bias exists for the reduced pelvic girdle (innominate) in many cetaceans [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

A New Ophthalmosaurid (Ichthyosauria) from Svalbard, Norway, and Evolution of the Ichthyopterygian Pelvic Girdle

et al. 2017

Self Cite

View full text Add to dashboard Cite

In spite of a fossil record spanning over 150 million years, pelvic girdle evolution in Ichthyopterygia is poorly known. Here, we examine pelvic girdle size relationships using quantitative methods and new ophthalmosaurid material from the Slottsmøya Member Lagerstätte of Svalbard, Norway. One of these new specimens, which preserves the most complete ichthyosaur pelvic girdle from the Cretaceous, is described herein as a new taxon, Keilhauia nui gen. et sp. nov. It represents the most complete Berriasian ichthyosaur known and the youngest yet described from the Slottsmøya Member. It is diagnosed on the basis of two autapomorphies from the pelvic girdle, including an ilium that is anteroposteriorly expanded at its dorsal end and an ischiopubis that is shorter or subequal in length to the femur, as well as a unique character combination. The Slottsmøya Member Lagerstätte ichthyosaurs are significant in that they represent a diverse assemblage of ophthalmosaurids that existed immediately preceding and across the Jurassic–Cretaceous boundary. They also exhibit considerable variation in pelvic girdle morphology, and expand the known range in size variation of pelvic girdle elements in the clade.

show abstract

Morphology and orientation of the ichthyosaurian femur

Cited by 18 publications

References 17 publications

A New Upper Jurassic Ophthalmosaurid Ichthyosaur from the Slottsmøya Member, Agardhfjellet Formation of Central Spitsbergen

A New Upper Jurassic Ophthalmosaurid Ichthyosaur from the Slottsmøya Member, Agardhfjellet Formation of Central Spitsbergen

SimbirskiasaurusandPervushovisaurusreassessed: implications for the taxonomy and cranial osteology of Cretaceous platypterygiine ichthyosaurs

A New Ophthalmosaurid (Ichthyosauria) from Svalbard, Norway, and Evolution of the Ichthyopterygian Pelvic Girdle

Contact Info

Product

Resources

About