Eva B. Koppelhus

The First Late Cretaceous Footprints from the Nemegt Locality in the Gobi of Mongolia

In September 2001, large ornithopod footprints were found in the Nemegt Formation at the locality known as Nemegt in the Gobi of Mongolia. Additional hadrosaur ichnites, plus footprints of sauropods and theropods, have been recovered since then. The Nemegt Formation is known for the number and diversity of dinosaur skeletons found there, but footprints have never before been reported. Footprints were noted in three horizons within the formation, and occur at the top of upward-fining successions of floodplain sandstones and mudstones of a meandering fluvial paleoenvironment. Most of the footprints are preserved as natural casts that show good preservation of detail. Skin impressions are found on some, and many have slide marks. The vast majority of the footprints can be identified as having been made by Saurolophus, but two footprints each of Tarbosaurus and Opisthocoelicaudia were also recovered. Three hadrosaur footprints were found in the quarry of a Tarbosaurus skeleton. It appears that after the Tarbosaurus had died and been partially buried, its skeleton was trampled by a hadrosaur. The overwhelming domination of hadrosaurs at the footprint levels suggests there are preservational biases acting on the fossilization of Nemegt skeletons to produce abnormally high predator/prey ratios.

Hands, feet and behaviour in Pinacosaurus (Dinosauria: Ankylosauridae)

Structure of the manus and pes has long been a source of confusion in ankylosaurs, owing to the imperfect preservation or complete lack of these parts of the skeletons in most specimens, and the fact that many species appear to have undergone a reduction in numbers of digits and phalanges. New specimens of Pinacosaurus from Alag Teeg in Mongolia confirm that the phalangeal formula of the manus is 2-3-3-3-2. However, there are only three toes in the pes, which has a phalangeal formula of X-3-3/4-3/4-X. Importantly, the number of phalanges in the third and fourth pedal digits can vary between either three or four per digit, even within the same specimen. The Alag Teeg site has yielded as many as a hundred skeletons of the ankylosaur Pinacosaurus, most of which were immature when they died. Each skeleton is preserved in an upright standing position, with the bones of the lower limbs often in articulation. The remainder of the skeleton, including the upper parts of the limbs, is generally disarticulated and somewhat scattered. Based on the presence of large numbers of juvenile Pinacosaurus specimens at Alag Teeg, as well as other Djadokhta-age sites (Ukhaa Tolgod in Mongolia, Bayan Mandahu in China), it seems juvenile Pinacosaurus were probably gregarious.

Perinate and eggs of a giant caenagnathid dinosaur from the Late Cretaceous of central China

The abundance of dinosaur eggs in Upper Cretaceous strata of Henan Province, China led to the collection and export of countless such fossils. One of these specimens, recently repatriated to China, is a partial clutch of large dinosaur eggs (Macroelongatoolithus) with a closely associated small theropod skeleton. Here we identify the specimen as an embryo and eggs of a new, large caenagnathid oviraptorosaur, Beibeilong sinensis. This specimen is the first known association between skeletal remains and eggs of caenagnathids. Caenagnathids and oviraptorids share similarities in their eggs and clutches, although the eggs of Beibeilong are significantly larger than those of oviraptorids and indicate an adult body size comparable to a gigantic caenagnathid. An abundance of Macroelongatoolithus eggs reported from Asia and North America contrasts with the dearth of giant caenagnathid skeletal remains. Regardless, the large caenagnathid-Macroelongatoolithus association revealed here suggests these dinosaurs were relatively common during the early Late Cretaceous.

Upper Cretaceous palynostratigraphy of the Dry Island areaThis article is one of a series of papers published in this Special Issue on the theme Albertosaurus.

The overall palynology of the upper Horseshoe Canyon Formation to lower Scollard Formation within the Edmonton Group is reviewed providing new insights into biostratigraphic relationships for the interval, including the recognition of unconformities in the stratigraphic package. The palynomorph recovery from the Horseshoe Canyon Formation and overlying units documents a number of significant events that allow the subdivision of the section. The Albertosaurus bonebed occurs within the lower Maastrichtian portion of the Edmonton Group. The bonebed is situated just below the base of the Scollardia trapaformis Palynomorph Zone, an important marker assemblage that has been documented from areas of the Yukon, Northwest Territories, Alberta, and Saskatchewan. This indicates that the bonebed lies at the top of the Mancicorpus vancampoi Zone. The transition between the zones is marked by a colour change in the sediments, the appearance of coals and organic-rich sediments above the transition, a decrease in numbers...

Introduction to Albertosaurus Special Issue

This special issue is being published to mark the passage of a century since Barnum Brown made a remarkable discovery in the badlands of Alberta. Brown was from the American Museum of Natural History (AMNH) in New York, and he had come to Alberta the previous year (1909) to check a report of dinosaur bones near the present-day town of Drumheller. He had been impressed enough to mount an expedition that set off in a flat-bottomed scow down the Red Deer River on August 3, 1910. As they floated downstream, they frequently stopped and looked for fossils in the badlands. On August 11th, they found what they thought was much of an Albertosaurus skeleton in hard rock. They realized by the next day, however, that they were in fact excavating the well-preserved bones of several individuals. In his fieldnotes, Brown’s assistant Peter Kaisen noted that the “whole top of a hill is nothing but a mass of bone. There are four hind feet in sight, vertebrae, and a lot of limb bones.” On September 4th, they loaded eight boxes of bones (the product of 29 man-days spent in the bonebed) on the scow and floated the expedition farther downstream. The specimens were shipped to New York, where they were prepared, put on display for a short time, and then mostly forgotten. Although Brown occasionally mentioned the 1910 discovery in papers (Brown 1914; Matthew and Brown 1923) and …