February 1, 2013
"LIFE IN A
DINOSAUR-DOMINATED ENVIRONMENT: Examining Life in
Maryland's Early Cretaceous (~110 Million Years Ago)"
Eighteen years of collecting
and analysis of over 1,000 of Maryland's Lower Cretaceous
(Potomac Group, Patuxent Formation, Aptian Age) reptile and
mammal footprints and trackways, along with vertebrate body
fossils, invertebrate fossils, and plant fossils, has yielded
surprising and important insight about a broad spectrum of life
about 110 million years ago. A huge dinosaur-dominated deltaic
floodplain in a semi-tropical environment is here shown to have
supported a minimum of around thirty dinosaur species coexisting
along with a vast array of other fauna, including unexpectedly
large mammals, as well anticipated small varieties.
Footprint and body fossil evidences reveal that the area was a
nesting ground for a broad range of fauna, including diverse
dinosaurs and pterosaurs (known popularly as pterodactyl).
Surprisingly, footprint and feeding trace evidences suggest that
among flight-capable fauna, pterosaurs largely outnumbered
birds. Along with pterosaur footprints of widely varying size,
and suggesting at least three basic footprint shapes, we find
the largest imprint (made by a front foot) yet described from
anywhere. Feeding traces of pterosaurs of correspondingly huge
size further suggest flying reptiles that were possibly at or
very near the very upper limit of pterosaur body-weight and
wingspan. Those Washington, D.C. metropolitan area discoveries
suggest that the pterosaur size-evolution clock should perhaps
be reset because it had been thought the largest pterosaurs did
not appear until Upper Cretaceous time.
Broader insights, resulting from examination of fossilized plant
materials, invertebrate traces, and insect evidences provide an
even more comprehensive perspective on Lower Cretaceous life in