Tuesday, 24 September 2019

MIDDLE TRIASSIC AMMONOID & BELEMNITE

A beautiful plate with a lovely example of the Middle Triassic ammonoid and belemnite from Fossil Hill in the Humboldt Mountains of Nevada. This locality is perhaps the most famous and important locality for the Middle Triassic (Anisian/Ladinian) of North America.

This was the site of the 1905 Expedition of the University of California’s Department of Geology in Berkeley funded by the beautiful and bold, Annie Alexander, the women to whom the UCMP owes both its collection and existence. J. P. Smith joined the expedition, though he was interested in the invertebrate fauna, not the mighty marine reptiles that helped get the project funded.

J.P. Smith published on the marine fauna in the early 1900s. They formed the basis for his monograph on North American Middle Triassic marine invertebrate fauna published in 1914.

N. J. Siberling from the US Geological Survey published on these outcrops in 1962. His work included nearly a dozen successive ammonite faunas, many of which were variants on previously described species. Evidently, his collections consisted mainly of weathered material and were made without stratigraphic control because he believed that most, if not all, of these species, were coexistent. The fossiliferous beds found here, as well as localities in north-western Nevada, were designated the 'Daonella dubia' zone. Dubious would be closer to the truth. Smith joined the 1905 Expedition of the University of California’s Department of Geology in Berkeley funded by the beautiful and bold, Annie Alexander, the women to whom the UCMP owes both its collection and existence.