Discoserra pectinodon
Class Actinoptergyii, Order Guildayichthyformes, Family Guildayichthyidae
Geological Time: Mississippian (~320 m.y.a.)
Size: Fish fossil is 62 mm long on a 185 mm by 95 mm and 150 mm by 120 mm matrix pair
Fossil Site: Heath Shale Formation, Bear Gulch Limestone, Fergus County, Montana
 Description:
The Bear Gulch Limestone is a deposit of some 70 square km in
extent
and 30 m in depth that has been a source of one of the most diverse
assemblages of fossil fish with some 110 species having been described
over the past 30 years. Most were new to science, and provided a
unique view of the marine environment of Mississippian times.
Fine preservation
of both fish and invertebrates is a hallmark of these deposits, presumably
due to an anoxic depositional environment. This fine specimen
is a
rare example of Gulidayichthyformes. The order and family was erected
in 2000 to accommodate this unusual taxon which possesses an unusual
mixture of primitive and modern characters in the skull bones. Note
the detailed rhombic ganoid type scales and comb-like teeth. The
species
derives its name from the long teeth which presumably aided it in
feeding, possibly on sponges. Overall, this is an exceptionally
beautiful fish fossil and example
of the type, rendered all the more desirable by the
fact
that both the part and counterpart examples are preserved. |
