David J. Varricchio
Montana State University
Publications 76
#1William J. Freimuth (MSU: Montana State University)
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
Abstract We describe the diversity and abundance of insect (specifically hymenopterans and coleopterans) pupation structures in the Upper Cretaceous (Campanian) Two Medicine Formation at the Egg Mountain locality, western Montana, U.S.A., an important dinosaur nesting site. The study interval comprises a massive calcareous siltstone and indurated silty limestone horizons interpreted as the product of cumulative paleosols. A 7 m by 11 m area was quarried with a jackhammer at intervals of 12.5 cm ...
#1L.J. Krumenacker (ISU: Idaho State University)
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
Last.Ashley L. Ferguson (ISU: Idaho State University)
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Abstract Vertebrate assemblages from the mid-Cretaceous (Albian-Cenomanian) Wayan Formation of Idaho and Vaughn Member of the Blackleaf Formation of Montana are dominated by the small burrowing dinosaur, Oryctodromeus cubicularis . Specimens can be assigned to three distinct taphofacies dependent on degrees of skeletal articulation and associated lithofacies. Taphofacies A comprises mostly to fully articulated specimens in bioturbated sandstones. Taphofacies B comprises partially articulated to ...
#1Christian Thomas Heck (OSU: Oklahoma State University–Stillwater)H-Index: 1
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
Last.John R. Horner (Chapman University)H-Index: 41
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#2David J. Varricchio (MSU: Montana State University)H-Index: 28
ABSTRACTOryctodromeus cubicularis is a small-bodied ornithischian dinosaur from the mid-Cretaceous Blackleaf and Wayan Formations of Montana and Idaho, respectively, and is the only documented dinosaur with evidence of a burrowing ecology. The type locality, from the Blackleaf Formation of southwestern Montana, consisted of an infilled burrow structure containing the disarticulated skeletons of one adult and two juveniles and represents a rare association of body fossils and trace fossils of a s...
#1David J. Varricchio (MSU: Montana State University)H-Index: 28
#2Martin Kundrát (University of Pavol Jozef Šafárik)H-Index: 11
Last.Jason Hogan (MSU: Montana State University)H-Index: 1
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Non-avian dinosaurs such as oviraptorosaurs and troodontids share several important reproductive characters with modern birds, including eggshell microstructure and iterative egg production. Nevertheless, debate exists concerning their incubation strategies. Here we estimate incubation period for the troodontid, Troodon formosus, by examining a near-term embryonic tooth. Synchrotron scanning and histologic thin sections allowed counting of daily (von Ebner) growth lines. The tooth preserves 31 i...
#1Ashley L. Ferguson (ISU: Idaho State University)
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
Last.Alex J. Ferguson (UIdaho: University of Idaho)
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ABSTRACTNesting localities of extant birds and reptiles may provide taphonomic models for interpreting nesting sites of ancient archosaurs. Here we describe assemblages of nesting gulls (Larus delawarensis and L. californicus), American white pelicans (Pelecanus erythrorhynchos), and double-crested cormorants (Phalacrocorax auritus). Seventy nests yielded 2752 skeletal elements and 2308 eggshells. Most material was located inside the nest for gulls and consisted of osteologically mature gull bon...
#1Jason R. Moore (UNM: University of New Mexico)
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
ABSTRACT Fluvial transport is recognized as a common manner by which bone assemblages forming in or near moving water can be taphonomically modified. Here we study an assemblage of 38 cow carcasses, killed during a mass-mortality event and deposited in a fluvial system (the Yellowstone River of eastern Montana), over the course of three years. Seven of the 38 carcasses were observable throughout the study, allowing assessment of patterns of disarticulation and element loss with respect to time a...
#1Frankie D. Jackson (MSU: Montana State University)H-Index: 19
#2David J. Varricchio (MSU: Montana State University)H-Index: 28
Abstract Two closely associated egg types occur at the same locality in the Upper Cretaceous (Maastrichtian) St. Mary River Formation in north central Montana. These specimens represent the first fossil eggs described from this formation. At least fifteen small ovoid eggs or egg portions are scattered through a 25 cm interval of rock. Five significantly larger, round eggs overlie these smaller eggs and are in close proximity to one another on a single bedding plane. The best preserved egg of the...