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A tyrannosaurid pedal ungual from the Williams Fork Formation (Campanian) of Colorado and its implications for the biogeography of Laramidian dinosaurs

Yun Chan-Gyu

Acta Geologica Polonica

2023

Vol. 73, no. 1

63--72

A right theropod pedal ungual phalanx II-3 from the Campanian Williams Fork Formation of northwestern Colorado is described, and a combination of features, including the large size, tapering distal tip, robust and stout overall form, triangular cross-section, and a relatively flat ventral surface allows a confident referral to Tyrannosauridae Osborn, 1906. Although this specimen was found in a relatively southern state, the proximal articular surface of this ungual is similar to that of Gorgosaurus libratus Lambe, 1914, a taxon found in the northern state, Alberta. Although based on limited evidence, this may suggest that the range of tyrannosaurids considered endemic to the north of Laramidia extended farther south than previously thought.

Genus-level versus species-level extinction rates

Trammer J.

Acta Geologica Polonica

2016

Vol. 66, no. 3

261--265

The average extinction rates of index species per m. y. are computed by means of a count-of-biozones metric (Trammer 2014). These rates and the average extinction rates of genera belonging to biostratigraphically important groups, calculated according to three different methods, show congruent rises and falls from the Cambrian to the Neogene. The extinction rates of genera are, thus, a relatively good predictor of species extinction rates.

Zapis kopalny grzybów i organizmów grzybopodobnych

Kopczyński K.

Przegląd Geologiczny

2006

Vol. 54, nr 3

231-237

The fossil record of fungi is now available from all Phanerozoic periods. In this paper, the most important and interesting taxa from subsequent periods were reviewed, to elucidate recognition of some of directions of fungal and pseudofungal evolution in changing paleoecosystems. In the three decades since the publication of the classical Pirozynski's paper (1976), many new taxa of fossil fungi have been discovered. Our knowledge of their relationships with other co-existing organisms has also expanded. Records of fossil Oomycota and Chytridiomycota are known from Precambrian. According to Retallack (1994), some of Ediacaran fossils can be interpreted as lichens. All presently known main groups of fungi were represented in the Paleozoic. Records of Glomales (Redecker et al., 2000) in Ordovician rocks seems to have a special significance for research on the evolution of mycorrhiza. This group of fungi can be respected as potential partners of mycorrhizal interactions with first terrestrial plants. Great diversity of fungi existed during the Mesozoic. During the Cenozoic (the only time span with fungal fossils reported from Poland), with diversification of climatic conditions and development of plant assemblages, they achieved the present stage of development.