David C. Parris

A New Species of Borealosuchus (Crocodyliformes, Eusuchia) from the Late Cretaceous—Early Paleogene of New Jersey

ABSTRACT A lower jaw and associated postcranial remains from the Late Cretaceous—early Paleocene Hornerstown Formation of New Jersey form the basis of a new crocodyliform species, Borealosuchus threeensis. Although one of the oldest known species of Borealosuchus, phylogenetic analysis supports a closer relationship to Borealosuchus from the early Eocene than with other Late Cretaceous or early Paleocene forms. This is based on the shared presence of a short mandibular symphysis excluding the splenial, a small external mandibular fenestra, and ventral osteoderms composed of two sutured ossifications. It is also similar to Borealosuchus material from the Paleocene of western Texas, though conspecificity cannot be demonstrated at present. A close relationship with the basal alligatoroids Leidyosuchus or Diplocynodontinae is not supported. The distribution of lower jaws with very small slit-like external mandibular fenestrae, or no fenestrae at all, among basal crocodylian lineages (including Borealosuchus) and close crocodylian relatives suggests the fenestrae may have been ancestrally absent in Crocodylia and regained two or more times. Current phylogenetic hypotheses are consistent with dispersal of more-derived species of Borealosuchus to the Western Interior during the Paleocene, and they indicate the presence of several unsampled lineages crossing the Cretaceous-Paleogene boundary.

The Marine Crocodilian Hyposaurus in North America

Publisher Summary This chapter discusses the marine crocodilian Hyposaurus in North America. The fossil genus Hyposaurus, a longirostrine mesosuchian crocodilian, is a characteristic and relatively common fossil from marine sediments of Maastrichtian through Danian ages. Its geographic range in the United States now extends from New Jersey to Alabama, in glauconite and chalk facies. A specimen that comprises the most perfectly preserved skull and jaws of Hyposaurus rogersii is analyzed. A diminutive seventh mandibular tooth is present only in the right dentary and it is completely absent from the left. This reduction of the seventh mandibular tooth is a synapomorphy of the Dyrosauridae. The edge of each dentary is slightly festooned. The mandibular symphysis varies from quadrangular to oval in transverse section, and is slightly wider than high. The type specimen of Hyposaurus fraterculus Cope is now known to be a juvenile Thoracosaurus, leaving H. rogersii Owen as the only North American species. It is notable as a marine guide fossil of short stratigraphic range, which does, however, span the Cretaceous-Tertiary boundary. It is found that one well-preserved specimen has yielded remarkably large gastroliths, prompting comparison to those of elasmosaurs, with potential contributions to stability in marine environments.

Alphadon (Marsupialia) and Multituberculata (Allotheria) in the Cretaceous of eastern North America

ABSTRACT Discoveries at the Ellisdale Site (Campanian, Marshalltown Formation) in New Jersey add significantly to knowledge of vertebrate microfaunas east of the Cretaceous Interior Seaway. Lizard and amphibian remains from Ellisdale appear congeneric with taxa known from western sites. Mammals in the Ellisdale Local Fauna include multituberculates and a marsupial. Two of the teeth thus far recovered are indistinguishable from specimens referred to Alphadon lulli (Marsupialia) and Cimolomys cf. C. clarki (Multituberculata), species known from western faunas of Judithian age.

Partial Dentition of a Chimaeroid Fish (Chondrichthyes, Holocephali) from the Upper Cretaceous Niobrara Chalk of Kansas, USA

Abstract A specimen collected in 2006 from the Smoky Hill Chalk of central Kansas, USA, represents a rare occurrence of a chimaeroid fish from the Niobrara Chalk. The associated material includes associated right and left vomerine plates, and the right palatine plate. Comparison of the Kansas vomerines with the type of “Edaphodon” laqueatus, a right vomerine from Lower Campanian strata of eastern Mississippi, indicates that the remains are conspecific. However, our analysis also shows that these vomerine plates are distinct from Edaphodon, principally because of a massive, hammer-like beak, and overall modification of the oral surfaces into flat crushing plates, rather than oblique shearing surfaces as seen in Edaphodon. In addition, whereas there are three large tritors on an Edaphodon palatine, the Niobrara palatine has four very small tritors, with two inner tritors, a middle tritor, and an outer tritor. Our conclusion is that the original taxonomic designation, Eumylodus laqueatus Leidy, 1873, is valid, and the geographic distribution of the taxon extended from the Mississippi embayment to the central portion of the Western Interior Seaway, U.S.A.

A juvenile Mastodon skull from Monmouth County, New Jersey

ABSTRACT. We report on the partial skull of a small juvenile Mammut americanum Kerr from the Monmouth brooks area of New Jersey. Most Pleistocene mammal specimens from the brooks occur as disarticulated fragments. This specimen, the left side of a skull, includes portions of the premaxillae, maxillae, nasals, lacrimals, frontals, and four teeth: three sequential deciduous premolars and the permanent tusk. The skull bones are loosely articulated and essentially unfused, and the reconstructed skull shows gaps representing unossified growth zones between bones. The two anterior left deciduous teeth (DP2 and DP3) are much worn and very fragile, while the posterior left deciduous tooth (DP4) is essentially unworn. The crypt for the left first molar (M1) is partially preserved. The interior of the braincase is characterized by shallow pitting; it is neither smooth nor does it show molding against gyri and sulci of the brain. The pits are not characteristic of the inner surface of a normal mammalian skull, and appear to represent lytic lesions due to a disease process. Radiocarbon dating of the skull yielded an age of 11,680 ± 30 years.