Dinosaur Dreaming

1999 dig report

Lesley Kool
Dinosaur Dreaming co-ordinator

Overall, the 1999 Dinosaur Dreaming field season was an unqualified success. After the frustrations experienced in the 1998 field season, this year's excavations developed very smoothly. The modified construction, introduced in 1998, took less than a week to install, compared to more than three weeks the previous field season. Once installed, it prevented at least 75% of the sand re-entering the excavations during high tides, saving at least two hours of digging wet sand each day.

Doris Seegets-Villiers continued collecting data for her research into the taphonomy of the site. She was greatly assisted by a laser level system, designed by Nick van Klaveren which, despite a few teething problems, resulted in speeding up the data collection process. Doris was also able to collect valuable data on a number of fossil bones found in situ which will eventually help her to build a three-dimensional computer model of the site.

Of course the main objective for the fieldwork is to collect fossil bones and this year proved our most successful to date. Not only were 630 fossil bones and teeth catalogued in the field, but included in that number were three tiny mammal jaws.

When the first mammal jaw was discovered during the 1997 field season, we hoped that it would not prove to be the only evidence of this exciting group of animals. Fortunately, this was not the case as three more jaws were found in 1998 during a re-examination of unprepared specimens collected during earlier field seasons.

Dr. Tom Rich compared the three new jaws with the original jaw of Ausktribosphenos nyktos, and concluded that at least one of them represented a new group of mammals called eupantotheres. This group is thought to be ancestral to the modern mammals.They have previously been found in Jurassic and/or Cretaceous rocks on all other continents except Antarctica. But they are only associated with placental mammals at one other place, the Early Cretaceous site at Khovboor, Mongolia.

A second paper was published in Records of the Queen Victoria Museum Launceston in January 1999. Entitled Early Cretaceous Mammals from Flat Rocks, Victoria, Australia by Thomas H. Rich et al., it describes the first four mammal jaws discovered and officially names the eupantothere jaw as Teinolophos trusleri, honouring the artist Peter Trusler for his accurate portrayals of many of the fossil animals discovered in the Early Cretaceous rocks of Victoria.

Progress Report

Dr. Tom Rich,
Museum Victoria

Three more mammalian dentary fossils were recovered from the Flat Rocks locality in 1999. Each had only one or two teeth in them and the dentaries themselves were quite incomplete. They were significantly smaller and less complete than the first three mammal dentaries found. That such specimens are now being recovered is a testimony to the thoroughness with which the fossil-bearing rock is now being examined. The rock is now being broken down manually to the size of single sugar cubes. This is about a tenth the minimum size that was formerly the one where no further work was done on a rock.

One of these new mammals is clearly the middle lower molar of Ausktribosphenos nyktos, the possible placental mammal from Flat Rocks. It adds valuable information about the variation to be expected on that tooth, information that will help determine just what A. nyktos is.

The second new mammal has a premolar quite unlike Ausktribosphenos nyktos. Yet a damaged molar preserved on the same dentary suggests it is A. nyktos. How to interpret this specimen is uncertain. Possibly the premolar is a deciduous one of A. nyktos and the previously known ones are permanent ones or it could be the other way around. (Deciduous teeth are those that fall out, that is, baby teeth.) Or it could be a mammal altogether different from A. nyktos.

The third new mammal is a jaw fragment with two teeth. It is such a difficult specimen to extract from the rock that Mr. Chuck Schaff from Harvard University flew to Australia at the end of September to help Lesley Kool prepare it. We do not know what kind of mammal it is.