Thunder lizard handstands: Manus-only sauropod trackways from the Glen Rose Formation (Lower Cretaceous,Kendall County,Texas)

Abstract

Three parallel, manus-only sauropod trackways from the Coffee Hollow A-Male tracksite (Glen Rose Formation, Kendall County, Texas) were studied separately by researchers from the Heritage Museum of the Texas Hill Country and the Houston Museum of Natural Sciences. Footprint and trackway measurements generally show good agreement between the two groups’ data sets. Footprints appear to be shallowly impressed true tracks rather than undertracks. One of the Coffee Hollow trackways shows marked asymmetry in the lengths of paces that begin with the left as opposed to the right forefoot, and two of the Coffee Hollow trackways are unusually broad. The Coffee Hollow trackways differ enough from the manus portions of other Glen Rose Formation sauropod trackways to suggest that they were made by a different kind of sauropod. Greater differential pressure exerted on the substrate by the forefeet than the hindfeet probably explains the Coffee Hollow trackways, like other manus-only sauropod trackways, but the possibility that they indicate unusual locomotion cannot at present be ruled out.     

Essay review

Crocodilian Biology and Evolution, edited by Gordon C. Grigg, Frank Seebacher, and Craig E. Franklin, 2001. Surrey Beatty and Sons (43 Rickard Road, Chipping Norton 2170 NSW, Australia), x+446p. ISBN 0-949-324 89-2 (hardback), Aust$99     

The Dinosauria,an updated compendium that matches its subject in scale and scope

The palaeoecology of a sequence of five closely spaced mammalian assemblages in the English Late Eocene Bembridge Limestone Formation is studied using cladistic, seriation and ecological diversity methods, after assessing the collecting and taphonomic biases. Analysis of this sequence is important as it is temporally close to the terminal Eocene global cooling event. It is concluded that the assemblages probably reflect quite closely the species composition of the original living communities and that they indicate habitats ranging from an open wooded environment to dense forest. The oldest assemblage (limestone facies) indicates open wooded habitat and contains earliest occurrences of certain taxa in the English Eocene; these represent northward dispersal from southwestern Europe in response to changing climate. The more forested habitats occur higher in the sequence and are characterised by ‘Lazarus’ taxa, suggesting reversion to earlier existing environments. Small scale changes appear to relate to local events, whereas more major ones may result from global climate change. Certain pairs of closely related species are segregated in different assemblages which are habitat distinctive, a conclusion not available from their morphologies.     

Speculations about the carrion‐locating ability of tyrannosaurs

Tyrannosaurs and other large carnivorous dinosaurs were probably opportunistic flesh‐eaters, both attacking live prey and also consuming carrion. As tall bipeds, tyrannosaurs may have been better able to locate carcasses than were their shorter contemporaries. By carrying their heads well off the ground, tyrannosaurs may have been able to spot dead animals a greater distance away from themselves than could shorter carnivores, and their line of sight to a carcass was less likely to have been blocked by ground vegetation. In addition, the elevated position of the nostrils of a tyrannosaur may have permitted the dinosaur more quickly to detect the scent of carrion than was possible for carnivores whose noses were closer to the ground.