Palynologists lingering over a cup of coffee earlier this year while listening to the radio may have heard a familiar voice. Dr. W. A. S. Sarjeant, long-time CAP member, appeared on the CBC Radio science programme "Quirks and Quarks" on Saturday, March 26th, 1994. Dr. Sarjeant was interviewed by host Bob MacDonald about his work on vertebrate footprints from Eocene sediments in Texas, recently reported in Sarjeant and Langston (1994).

This is the richest assemblage of vertebrate footprints of Tertiary age in North America and includes tracks from nineteen types of mammals, two turtle taxa, six types of birds, and two invertebrate taxa. These footprints are extremely varied and well-preserved and range in size from 0.5 m to about 3 mm. The tiny footprints, about the size of those made by a small mouse, are the smallest mammal footprints of this age so far identified. Interestingly, the taxa identified include a surprisingly high proportion of carnivores, five out of nineteen taxa. The tracks were made in a mudflat formed from freshly fallen layer of volcanic ash, wetted by rainfall. The mud subsequently hardened, preserving the tracks, and formed a 3 m thick tuff bed. This is similar to the mechanism invoked for the preservation of the remarkable hominid tracks of Laetoli (Leakey 1981:40-42).

Dr. Sarjeant points out that mammal footprints are a neglected area of research compared to the study of dinosaur tracks. Mammal footprints can provide valuable information on the structure of the foot, pads and claw configuration for example. These types of soft tissues are not preserved in the fossil record. Hence the study of mammal tracks can yield data on foot structure and the mechanics of locomotion that are not available from other sources. The pattern and relationships of the various tracks can also give a picture of behaviour. In contrast, in the case of dinosaurs, foot structure is comparatively well-known from the fossil record and the tracks give supplementary information on locomotion and behaviour. Dr. Sarjeant hopes to continue this work during an upcoming six-month sabbatical, when he plans to investigate a rich assemblage of vertebrate tracks preserved in Oligocene sediments in Texas.

Incidentally, anyone interested in early mammals may also want to look at the April 1994 issue of Natural History (Vol. 103, No. 4), entitled "The Rise of Mammals". The issue contains many interesting reconstructive paintings and a number of articles discussing several aspects of mammal history. One article includes some mention of footprints!

It is good to see earth sciences receiving national media attention. Dr. Sarjeant is to be congratulated for continuing to promote geology to the general public.

Reference

Leakey, R. E., 1981. The Making of Mankind. E. P. Dutton, New York. 256 pp.

Sarjeant, W. A. S., and W. Langston Jr., 1994. Vertebrate Footprints and Invertebrate Traces from the Chadronian (Late Eocene) of Trans-Pecos Texas. Texas Memorial Museum Bulletin 36. Austin, Texas. 86 pp., 25 plates.

Alwynne B. Beaudoin
Edmonton, Alberta

---

Note: This article appeared in CAP Newsletter 17(1):12, 1994.