On the occurrence of fossil conifers with affinities to Geinitzia in the late Cretaceous (Campanian) Mesaverde Group, Williams Fork Formation of northeastern Utah, U.S.A.

In this paper we describe fossil conifer branches discovered in the Mesaverde Group, Williams Fork Formation in northeastern Utah, along Snake John Reef. Fossil conifers from the Campanian of northeastern Utah have not been previously studied, despite their common occurrence in the formation. The recovered fossils closely resemble Geinitzia known from the late Cretaceous of Europe, with several previous reported occurrences in North America, including New Jersey and Southern Utah. The fossils share morphological characteristics with Geinitzia , exhibiting short spirally arranged thin needles, with appressed scale-like leaves along the shoots. They differ from Araucarites in that the appressed needles are more scale like and smaller, and differ from the members of the modern Araucariaceae in lacking broad bases to the needles, although the fossils resemble the modern species Araucaria heterophylla (Norfolk Island Pine) native to the South Pacific. The observed branching pattern in the fossil reflects similarities found in the Cupressaceae Family, and Geinitzia may be regarded as an early member of this group, or having an affinity to fossil Araucariaceae conifers, which despite having a modern southern hemisphere geographic distribution today were widespread during the late Mesozoic, extending across North America and Europe.