Field notes I: 2013 - summer of Tyrannosaurus rex

Right frontal in dorsal view of a juvenile Tyrannosaurus rex (DDM-344.1) from the Hell Creek Formation of southeastern Montana that I found last August. Rostral is to the right, medial is toward the top of the image. Abbreviation: Dinosaur Discovery Museum, Kenosha WI.

Introduction

This series of posts will describe the upcoming Carthage College Expedition to the Hell Creek Formation of southeastern Montana. We have been collecting there since 2006 on exposures that are on sections managed by the Bureau of Land Management, and we leave for there in the morning!

Little Clint Quarry

This year we (myself, my technician, 10 students, 2 field assistants, 2 volunteers) resume excavation of a multitaxic and monodominant bonebed, the Little Clint Quarry (named for Thescelosaurus expert Dr. Clint Boyd).

Little Clint is the nickname of a partial skeleton of a juvenile T. rex that led to the bonebed. So far, we have collected a frontal, rib, tibia, and pedal phalanx of the specimen. We have also found a partial maxilla, a pair of tibiae, and a metatarsal III (see image below) belonging to a large T. rex, and a tooth and pedal phalanx of a medium-sized T. rex that we have nicknamed ‘Big Clint’.

In addition to T. rex, we have recovered a complete hadrosaurid fibula, a partial skeleton of Triceratops that includes cranial and postcranial bones, and two Thescelosaurus femora. The bonebed also includes nondinosaurian amniotes, including isolated bones of crocodilians and turtles. In some parts of the quarry the dinosaur bones are so densely concentrated that they are stacked upon each other. This year we will resume excavation of this lag deposit, and I am optimistic that we will recover at least a few additional bones of the large T. rex.

Partial left metatarsal III (DDM-35.131) in anterior view of a large Tyrannosaurus rex from the Little Clint Bonebed.

Little Hyslop Locality

Last summer I went prospecting with one of my long-standing volunteers, Mr. Andy Prell (Kenosha, WI) a few hours after the students left for home. About 15 minutes from camp I walked up a ravine, and to my astonishment, I saw a small tyrannosaurid frontal bone lying upside down on the slope (see image above). Andy joined me a few minutes later and searched upslope, where he found a partial pedal ungual (D I-1) of a small T. rex. Moments later I found a small T. rex tooth a short distance north of the frontal (see image below).

The bones and tooth correspond to the same size of animal, between 3 and 6 meters long, and so there is a good chance that at least a partial skeleton lies below the surface. Andy and I searched intently on the hillside for more evidence of the skeleton, without success. Several days later I returned to the locality with our team of volunteers, but again without finding anything else. I hope that this year’s spring rains have brought more of the specimen to the surface, unless Andy and I found the last of it. The Little Hyslop locality is named for Mr. Dan Hyslop (UW-Madison graduate).

The tooth (DDM-344.3) of a juvenile Tyrannosaurus rex that I found at the Little Hyslop Locality. It is consistent in size with the frontal bone, which suggests that there is more of the specimen to find.

I will make the best effort to keep you posted on our progress in the field, as far as T. rex discoveries are concerned!