Hadrosaurian Dinosaurs of North America

Abstract

The unarmored, hadrosaurian dinosaurs of the late Cretaceous of N orth America constitute an interesting group about which much has been written and many species described. A review of this literature showed many different angles of approach, and it was in part to reconcile these various descriptions and reduce them to certain comparable common factors that this monographic study was undertaken. Aside from the mere compilation of the literature of these dinosaurs, redescriptions were prepared, nearly always in the presence of the original types and such other asso ciated material as had come to light since the species was named.The authors also undertook as complete a m orphological study of the animals as the circumstances permitted, learning what they could of the mechanics of the skeleton and teeth, the musculature and integument, the nervous system and sense organs, and the probable functions of these various parts in the living animal. They further endeavored to imagine the reconstructed creatures in their appropriate environment-physical, climatic, vegetal, and animate-and to picture them and their manner of life as animate beings of a vanished age. An account of their dis tribution both in time and space is given, as well as a discussion of their probable phylogeny and the trend of their evolution.

Morphometric observations on hadrosaurid ornithopods

“…This is as would be expected from published discussions (Lull and Wright 1942;Brett-Surman 1979;Sereno 1986) that assume monophyly. The relatively higher similarities among the non-lambeosaurines may appear to contradict this, but, instead, only indicate the high degree of morphological evolution within the lambeosaurine line.…”

“…Family Hadrosauridae Subfamily Hadrosaurinae Anatotitan Brett-Surman, new genus A. copei (Lull and Wright 1942) Diagnosis: Skull longer and lower than in any other hadrosaur, muzzle wider than in any other hadrosaur, quadrate/ mandible ratio the smallest of all hadrosaurs, edentulous portion of the mandible relatively longer than in any hadrosaur, appendicular elements relatively longer and more gracile than in any hadrosaur of the same quadrate height, limb elements up to 10% longer than in an Edmontosaurus of the same quadrate height, neck of prepubis relatively longer and shallower than in any hadrosaur, postacetabular process more dorso-medially twisted and relatively shorter than in an Edmontosaurus of the same size.…”

“…The ischium is divided into three sections, the head, shaft, and foot, all represented by one or more polygons in the graphics. There are three types of footed ischia in hadrosaurs, not two as commonly believed (Lull and Wright 1942). The first is the lambeosaurine condition with a fully formed, distally expanded foot.…”

Discussion of Character Analysis of the Appendicular Anatomy in Campanian and Maastrichtian North American Hadrosaurids—Variation and Ontogeny

“…It is quite reduced in the type of Brachyhphosaurus, and scapulae referred to Shaulimgusiiiirus and T.inius sitwnsis. Illustrated scapulae of Corytbosaurus (Brown 1916;Lull and Wright 1942) and Edmontosaams (Gilmore 1914a;Lull and Wright 1942;Parks 1935) show significant variability in the degree of flaring of the scapula, and this is reported for Brachylophosakrus as well (Prieto-Marquez 2000, and this volume).…”

“…Hadrosaunds ot the same age group maintain the same scapular proportions relative the body throughout life. It would appear that this is accomplished solely by increasing the length and width of the scapular blade relative to the proximal por- (Brown 191 6;Lull and Wrig ht 1942) and Edm ontosaurus (Gilmo re 1924a;Lull and Wright 1942;Parks 1935) show sign ificant variability in the degree of flaring of th e scapula, and thi s is reported for Bracbylopbosaurus as well (Prieto-Marquez 2 000, and thi s volume) . It is imposs ible at th is time to distinguish morphological types that may be referred to specific genera or clad es because of inade quate sample size.…”