Leidyosuchus

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) ...

Abstract: The eusuchian Allodaposuchus is described from Late Cretaceous continental strata of southeastern France. Contrary to recent work involving this genus, a new and more derived position within Eusuchia is proposed in the present study. Allodaposuchus cf. A. precedens from southern France and Allodaposuchus precedens from Romania can be assigned to basal alligatoroids, but their relationship to other basal forms such as Leidyosuchus, diplocynodontids, and other basal globidontans remains unresolved. Most of the inconsistency in the position of Allodaposuchus within alligatoroids may be related to the presence of a laterally open canalis quadratosquamosoexoccipitalis in at least Allodaposuchus precedens from Romania, which also characterizes the basal eusuchian Hylaeochampsa. Although this character remains problematic, the combination of alligatoroid synapomorphies in Allodaposuchus supports its position within Alligatoroidea. The new Allodaposuchus specimen from France suggests the presence of a st...

Abstract: Fossil vertebrates have been described from the Paleocene of Big Bend National Park, Brewster County, Texas, by Wilson et al. (1952), Wilson (1967), Schiebout (1973, 1974), and Standhardt (1986). These studies focused on the mammalian component of the fauna, although crocodylian and chelonian remains are known. Schiebout (1973) referred a partial dentary to Diplocynodon. Teeth in the Black Peaks Formation were referred to Allognathosuchus by Straight (1996); Standardt (1986) discussed isolated crocodyliform teeth from across the Cretaceous-Tertiary Boundary in this area, but did not assign any of them to named taxa. Brochu (1996) briefly reviewed more complete remains, which were found to include an alligatorid and a member of Borealosuchus. The giant crocodylian Deinosuchus and a goniopholidid are known from underlying Cretaceous sediments (Rowe et al., 1992), and overlying Eocene units are known to preserve remains of the ziphodont taxon Pristichampsus (Busbey, 1986). A skull from the Paleocene Black Peaks Formation of Big Bend National Park can be referred to Borealosuchus. The name Borealosuchus is defined with reference to the monophyletic group including the last common ancestor of four crocodylians formerly classified as “ Leidyosuchus ” ( B. sternbergii, B. acutidentatus, B. wilsoni, B. formidabilis ) and all of its descendents (Brochu, 1997b). Borealosuchus is closely related to, but not a member of, a clade including living alligatorids and crocodylids (Wu et al., 1996, 1997; Salisbury and Willis, 1996; Brochu, 1997a,b). A phylogenetic review of these taxa (Brochu, 1997b) indicated that B. sternbergii is the basalmost member of this group, and that B. acutidentatus and B. wilsoni are sister taxa. Borealosuchus appears to include most, if not all, fossils from North America referred to Diplocynodon (Brochu, 1997b, 1999). To date, most occurrences of Borealosuchus have been from northern North America— B. sternbergii from …