Paleocene non-avian dinosaurs

Spencer G. Lucas ^1
1New Mexico Museum of Natural History, 1801 Mountain Road N.W., Albuquerque, New Mexico, USA.

Reports of Paleocene non-avian dinosaur fossils (hereafter simply Paleocene dinosaurs) were first published in the 1800s and, though not numerous, are now nearly global in distribution, having been claimed from all the continents except Australia and Antarctica. These reports fail to demonstrate the presence of Paleocene dinosaurs because of one or more of the following problems: (1) misidentifications of supposed Paleocene dinosaur fossils that are not dinosaurian; most of these misidentifications are of crocodilian fossils; (2) failure to establish a Paleocene age for the dinosaur fossils because of incorrect age data or stratigraphic position; and/or (3) failure to establish a clear association of dinosaur fossils that are not reworked with bona fide Paleocene fossils. It is not possible to determine with certainty whether a fossil tooth/bone is reworked because abrasion and other damage to the fossil is not a definite criterion for reworking. Thus, the supposed Paleocene dinosaur fossils from Montana, USA and the Chatham Islands in the southern Pacific are arguably reworked but not definitely reworked in the eyes of some palaeontologists. Still, there is no definitive evidence that these are not reworked dinosaur fossils, so there are no demonstrated Paleocene dinosaur fossils. Nevertheless, there is no reason theoretically why there should not be Paleocene dinosaur fossils, so the search for them will continue.