Turtles of the clade Pan-Testudinoidea have a rich fossil record in North America, including the Caribbean, ranging from the late Paleocene to the Holocene. All earlier reports cannot be substantiated herein. The earliest members of this clade probably immigrated in multiple waves from Asia. Current phylogenies of crown Testudinoidea recognize four primary clades: Pan-Emydidae, Pan-Geoemydidae, Pan-Testudinidae, and the lineage leading to Platysternon megacephalum. An updated global phylogeny allows attribution of fossils to these lineages with confidence that allows the discernment of new diversity trends and biogeographic patterns. The diversity of North American Pan-Testudinidae increased consistently throughout the Cenozoic and reached its peak in the early Miocene. The extinction of many testudinids at the end of the Pleistocene, however, decreased tortoise diversity toward its extant levels. The diversity of North American Pan-Emydidae and Pan-Geoemydidae shows opposite patterns. Pan-Emydidae are remarkably diverse today, but their diversity was low in the Eocene and only increased dramatically from the Oligocene and onwards. Pan-Geoemydidae, on the other side, were diverse in the late Paleocene to Eocene, but their diversity decreases to their extremely low present levels starting with the Oligocene. A taxonomic review of 191 named North and Central American pan-testudinoid taxa finds 57 nomina valida, 69 nomina invalida, 64 nomina dubia, and 1 nomen nudum.

The Barremian through Turonian record of tyrannosauroids in North America is sparse, and neither the western nor eastern portions of the continent have produced substantial material of early tyrant dinosaurs. This is unfortunate, as the discovery and description of several new tyrannosauroid genera from this temporal interval in recent years has shown that this period of time was likely when the tyrannosauroids evolved many of the signature features of the large- bodied genera that famously roamed the planet during the latest Cretaceous. One particular trait of the younger tyrant dinosaur genera that seems to have evolved during the aforementioned temporal interval was that of large body size. Here, I describe the metatarsal II of an indeterminate tyrannosauroid from the Cenomanian Potomac Formation of New Jersey. The metatarsal II is significant for several reasons. It is the only definite occurrence of a tyrannosauroid in eastern North America (Appalachia) before the Coniacian and Santonian and indicates an animal in the size range of tyrannosauroids from the Santonian to Maastrichtian of the Cretaceous. The New Jersey specimen thus differs from other, mostly small and gracile, known tyrannosaur genera of the mid-Cretaceous, suggesting that the evolution of large size among tyrannosauroids was a complex process. The metatarsal has morphological affinities to the corresponding metatarsal II of Appalachiosaurus montgomeriensis, and along with the results of phylogenetic analysis this suggests that Late Cretaceous Appalachian tyrannosauroids were relict forms isolated on the landmass.