Abstract The Carboniferous record of tetrapod footprints is mostly of Euramerican origin and provides the basis for a footprint biostratigraphy and biochronology of Carboniferous time that identifies four tetrapod footprint biochrons: (1) stem-tetrapod biochron of Middle Devonian–early Tournaisian age; (2) Hylopus biochron of middle Tournaisian–early Bashkirian age; (3) Notalacerta–Dromopus interval biochron of early Bashkirian–Kasimovian age; and (4) Dromopus biochron of Kasimovian–early Permian age. Particularly significant is the Carboniferous tetrapod footprint record of the Maritimes basin of eastern Canada (New Brunswick, Nova Scotia and Prince Edward Island), which encompasses well-dated and stratigraphically superposed footprint assemblages of Early Mississippian–early Permian age. The Carboniferous tetrapod footprint record provides these important biostratigraphic datums: (1) oldest temnospondyls (middle Tournaisian); (2) oldest reptiliomorphs, likely anthracosaurs (middle Tournaisian); (3) oldest amniotes (early Bashkirian); and (4) oldest high-fibre herbivores (Bashkirian). Carboniferous tetrapod footprints thus provide significant insight into some major events of the Carboniferous evolution of tetrapods.

Abstract Three fundamental terms in ichnology are: (1) assemblage, which is equivalent to an assemblage of body fossils; (2) ichnocoenosis, which is a trace fossil assemblage produced by a biological community that can be characterized by morphological criteria; (3) ichnofacies, which refers to recurrent ichnocoenoses that represent a significant portion of Phanerozoic time. There are five archetypal vertebrate ichnofacies for non-marine environments ( Chelichnus, Grallator, Carichnium, Batrachichnus, Characichichnos ) of which four are present in the Permian: (1) Chelichnus ichnofacies — Chelichnus ichnocoenosis; (2) Batrachichnus ichnofacies — Batrachichnus ichnocoenosis; (3) Brontopodus ichnofacies — Pachypes ichnocoenosis; (4) Characichichnos ichnofacies — Serpentichnus ichnocoenosis. The Chelichnus and Characichichnos ichnofacies occur throughout the Permian, the Batrachichnus ichnofacies is restricted to the Early Permian and the Brontopodus to the Middle to Late Permian. The Batrachichnus ichnocoenosis can be divided into the Ichniotherium sub-ichnocoenosis, Amphisauropus sub-ichnocoenosis and the Dimetropus subichnocoenosis, which represent a spectrum of non-marine environments from alluvial fan to tidal flat.

Abstract Permian tetrapod footprints are known from localities in North America, South America, Europe and Africa. These footprints comprise four ichnofacies, the Chelichnus ichnofacies from aeolianites and the Batrachichnus, Brontopodus and Characichnos ichnofacies from water-laid (mostly red-bed) strata. Permian track assemblages of the Chelichnus ichnofacies are of uniform ichnogeneric composition and low diversity, range in age from Early to Late Permian, and thus are of no biostratigraphic significance. Footprints of the Batrachichnus and Brontopodus ichnofacies represent two biostratigraphically distinct assemblages: (1) Early Permian assemblages characterized by Amphisauropus, Batrachichnus, Dimetropus, Dromopus, Hyloidichnus, Limnopus and Varanopus ; and (2) Middle to Late Permian assemblages characterized by Brontopus, Dicynodontipus, Lunaepes, Pachypes, Planipes , and/or Rhynchosauroides . Few Permian footprint assemblages are demonstrably of Middle Permian (Guadalupian) age, and there is a global gap in the footprint record equivalent to at least Roadian time. Permian tetrapod footprints represent only two biostratigraphically distinct assemblages, an Early Permian pelycosaur assemblage and a Middle to Late Permian therapsid assemblage. Therefore, footprints provide a global Permian biochronology of only two time intervals, much less than the ten time intervals that can be distinguished with tetrapod body fossils.

Sauropod dinosaurs have a temporally disjunct distribution in the North American Western Interior during Cretaceous time, here referred to as the sauropod hiatus. Sauropod body and ichnofossils are present in inland basinal and coastal deposits of Aptian-Albian age in Wyoming, Texas, Oklahoma, and Arkansas. Body fossils of sauropods (the titanosaurid Alamosaurus) occur in inland basinal deposits of Maastrichtian age in Texas, New Mexico, Utah, and Wyoming. No sauropods of Cenomanian-Campanian age are known from a Western Interior sedimentary record dominated by coastal deposits and essentially devoid of inland basinal deposits. Dinosaur ichnofaunas from late Albian coastal deposits in New Mexico, Oklahoma, and Colorado lack sauropod footprints, and thus suggest sauropod disappearance from Western Interior coastal environments by the end of Early Cretaceous time. These observations suggest two scenarios: (1) sauropods abandoned Western Interior coastal environments at the end of the Albian, but persisted in Western Interior inland basinal environments throughout Cretaceous time, or (2) sauropods became extinct in the Western Interior at the end of the Albian and reinvaded during the Maastrichtian. Choosing between these scenarios depends on an evaluation of negative evidence. However, the close phylogenetic relationship of Alamosaurus to South American titanosaurids, the absence of sauropod fossils in inland deposits of the Campanian Two Medicine and Judith River Formations, and the availability of a dispersal route between North and South America near the end of Cretaceous time support the second scenario. Thus, sauropods apparently became extinct in the Western Interior near the end of the Albian, then reinvaded from South America during the Maastrichtian but were only able to establish themselves in inland basinal environments. The extinction of sauropods in the Western Interior at the end of Early Cretaceous time may reflect an unrecognized terrestrial extinction coincident with the well-known severe marine extinction caused by a major late Albian regression.

Dinosaurs from the Upper Cretaceous Fruitland Formation and Kirtland Shale in the San Juan Basin, New Mexico, pertain to the following taxa: Ornithomimidae, cf. Ornithomimus edmonticus , cf. Struthiomimus altus , Dromaeosauridae, Albertosaurus sp., cf. Tyrannosaurus rex , Alamosaurus sanjuanensis , ?Pachycephalosauridae, Ankylosauria, Ankylosauridae, Nodosauridae, ? Euoplocephalus sp., ? Panoplosaurus sp., Hadrosauridae, Kritosaurus navajovius , Parasaurolophus tubicen , P. cyrtocristatus , Ceratopsidae, cf. Chasmosaurus sp., Pentaceratops sternbergii , P. fenestratus , and Torosaurus cf. T. utahensis. The dinosaur fauna of the Fruitland Formation is temporally equivalent to the dinosaur faunas of the Judith River (Montana) and Oldman (Alberta) Formations and is of late Campanian (Judithian) age. This correlation is based primarily on the absence in the Fruitland Formation of dinosaurs typical of post-Judithian dinosaur faunas elsewhere in western North America. The dinosaur fauna of the Kirtland Shale below the Naashoibito Member is virtually identical to that of the Fruitland Formation. Based on stratigraphic relationships, the Kirtland Shale must be younger than the Fruitland Formation and may be as young as Edmontonian (latest Campanian-early Maastrichtian) below the Naashoibito Member. The Naashoibito Member of the Kirtland Shale contains cf. Tyrannosaurus rex, Alamosaurus sanjuanensis, and Torosaurus cf. T. utahensis, taxa indicative of a Lancian (middle-late Maastrichtian) age. Therefore, Kritosaurus from the Naashoibito Member represents the youngest known occurrence of this genus. The Lancian age of the Naashoibito Member indicates that the unconformity at the base of the Ojo Alamo Sandstone is not of as great a temporal magnitude as most previous workers had believed. Thus, there is a nearly complete record of the Cretaceous-Tertiary transition in the west-central San Juan Basin, indicated by dinosaur-based correlation of the Fruitland and Kirtland Formations. This correlation is consistent with most other evidence, except magnetostratigraphy, that has been used to determine the age of the Fruitland and Kirtland Formations.