The smallest-known neonate individual of Tylosaurus (Mosasauridae, Tylosaurinae) sheds new light on the tylosaurine rostrum and heterochrony

  title={The smallest-known neonate individual of Tylosaurus (Mosasauridae, Tylosaurinae) sheds new light on the tylosaurine rostrum and heterochrony},
  author={Takuya Konishi and Paulina Jim{\'e}nez-Huidobro and Michael Wayne Caldwell},
  journal={Journal of Vertebrate Paleontology},
ABSTRACT We here report on the smallest-known, neonate-sized Tylosaurus specimen, FHSM VP-14845, recovered from the lower Santonian portion of the Niobrara Chalk exposed in Kansas, U.S.A. Lacking any associated adult-sized material, FHSM VP-14845 comprises fragmentary and associated cranial bones, here considered to represent a single neonatal individual with an estimated skull length of 30 cm. Despite its small size, a suite of cranial characters diagnoses FHSM VP-14845 as a species of… 

Craniofacial ontogeny in Tylosaurinae

An analysis of growth in Tylosaurus provides an opportunity to test hypotheses of the synonymy of T. kansasensis with T. nepaeolicus, sexual dimorphism, anagenesis, and heterochrony.

A Comprehensive Review of the Morphological Diversity of the Quadrate Bone in Mosasauroids (Squamata: Mosasauroidea), with Comments on the Homology of the Infrastapedial Process

A comprehensive comparison of mosasauroid quadrates contextualized against a recent phylogeny of the group is provided, and it is demonstrated that some features of the posteroventral region of these bones are likely homoplastic and require the establishment of a new set of anatomical terms.

Assessing ontogenetic maturity in extinct saurian reptiles

The various methods that have been used to assess maturity in every major saurian group are described, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method‐specific pitfalls, best practices, and fruitful directions for future research.



New Data on Cranial Measurements and Body Length of the Mosasaur, Tylosaurus nepaeolicus (Squamata; Mosasauridae), from the Niobrara Formation of Western Kansas

Tylosaurus nepaeolicus is one of the least well known of the five species of mosasaurs that are recognized from the lower Smoky Hill Chalk Member (upper Coniacian) of the Niobrara Formation in western Kansas but the two species are closer in size than previously reported.

Earliest record of the genus Tylosaurus (Squamata; Mosasauridae) from the Fort Hays Limestone (Lower Coniacian) of western Kansas

Abstract Fossil vertebrates are extremely rare in the Fort Hays Limestone member of the Niobrara Chalk in comparison to the rich variety of well-preserved fish, turtles, mosasaurs, pteranodons, and


The unexpected preservation of paired septomaxillae and the presence of a clear and well-defined vomer-pterygoid contact in UALVP 24240 are reported, allowing re-evaluation of the species composition of the genus.

Redescription and Rediagnosis of the Tylosaurine Mosasaur Hainosaurus pembinensis Nicholls, 1988, as Tylosaurus pembinensis (Nicholls, 1988)

It is reported that of the original 54 ‘pre-chevron’-bearing vertebrae, that 26 are from a second, unrelated species of mosasaur, and it is difficult, due to poor preservation, to identify which of these elements are pygals.

Reassessment and Reassignment of the Early Maastrichtian Mosasaur Hainosaurus bernardi Dollo, 1885, to Tylosaurus Marsh, 1872

The available data support the conclusion that Hainosaurus is a junior synonym of Tylosaurus because no anatomical features distinguish the former from the latter.

Tylosaurus kansasensis, a new species of tylosaurine (Squamata, Mosasauridae) from the Niobrara Chalk of western Kansas, USA

  • M. Everhart
  • Biology
    Netherlands Journal of Geosciences
  • 2005
Among the key differences separating this species from other tylosaurines are a shortened, more rounded pre-dental process of the premaxilla, a distinctive quadrate lacking an infrastapedial process, and a parietal foramen located adjacent to the frontal-parietal suture.

Two New Plioplatecarpine (Squamata, Mosasauridae) Genera from the Upper Cretaceous of North America, and a Global Phylogenetic Analysis of Plioplatecarpines

The current study recognizes 11 species within seven genera to constitute the Plioplatecarpinae, with as many as 17 unequivocal character changes support the clade comprising the three post-middle Campanian Plioplatedcarpus species.

Pelagic neonatal fossils support viviparity and precocial life history of Cretaceous mosasaurs

The recovery of these extremely young specimens from a pelagic setting indicates that even neonatal mosasaurs occupied open oceanic habitats and were likely born in this setting, and shed new light on the ecology of neonatalMosasaurs.

Redescription of the Holotype of Platecarpus tympaniticus Cope, 1869 (Mosasauridae: Plioplatecarpinae), and its Implications for the Alpha Taxonomy of the Genus

Re-characterization of the holotype reveals the following similarities to Platecarpus ictericus: exoccipitals-basioccipital suture transversely oriented in condylar view; basal tubera not inflated and widely separated along ventral midline; cervical intervertebral joint surface strongly curved; seventh cervical vertebra lacking articulating intercentrum.