A new genus and species of trigonotarbid arachnid, Gigantocharinus szatmaryi, was recovered from debris at the bottom of the Red Hill exposure. The gray-green siltstone in which this impression fossil is embedded suggest that it came either from the Floodplain Pond facies or a similar depositional environment. Gigantocharinus measures 7 mm in length and is tennatively assigned to the trigonotarbid family Paleocharinidae.
Trigonotarbids are an extinct group of arachnid arthropods whose record extends from the Silurian to the Lower Permian and are known from several localities in Europe and North America. They superficially resemble spiders. Both have eight legs and a pair of pedipalps (leg-like appendages near the head that are used for sensing, seizing and manipulating prey). They also have two main body parts (cephalothorax and abdomen). However, trigonotarbids lack the silk-producing spinnerets that have apparently been crucial to the spider's evolutionary success. They also have strongly segmented abdomen and don't exhibit the constriction that spiders have between the abdomen and cephalothorax.
- Mazon Creek trigonotarbid Pleophrynus ensifer:
- Hans Steur's paleobotany pages with images of a trigonotarbid Maiocercus celticus
- Univ. of Aberdeen's web page on a Rhynie Chert trigonotarbid:
- U.C. Museum of Paleontology web page on trigonotarbids:
- Scientific Papers:
- Shear, W. A. 2000. Gigantocharinus szatmaryi, a new trigonotarbid arachnid from the Late Devonian of North America (Chelicerata, Arachinida, Trigonotarbida). J. Paleont. 74(1): 25-31.
- Shear, W.A. and P. A. Selden. 2001. Rustling in the Undergrowth: Animals in Early Terrestrial Ecosystems. In: P. G. Gensel and D. Edwards (eds.), Plants Invade the Land: Evolutionary & Environmental Perspectives. Columbia Univ. Press, New York.
- Image Credits: