Late late Albian (Early Cretaceous) shark teeth from Annopol, Poland

摘要

Siversson, M. & Machalski, M., February 2017. Late late Albian (Early Cretaceous) shark teeth from Annopol, Poland. Alcheringa 41, 433-463.Screen washing of the condensed phosporite-bearing sands at the top of the Albian succession at Annopol, Poland, produced 789 selachian teeth of which 264 are determinable to at least genus level. The sediment type and methods of processing prevented recovery of small-toothed taxa, resulting in an assemblage comprising 13, mostly large-toothed taxa. Lamniformes dominates with Dwardius sp. being, by far, the most common taxon. Observations on vertical distribution and preservation of the teeth (with focus on the adhered phosphatic matrix), coupled with biostratigraphic ranges of co-occurring ammonites, indicate that the majority of the shark material is attributable to the Mortoniceras rostratum or, more probably, M. perinflatum Zone (late late Albian; mid-Vraconnian'). This is compatible with the composition of the shark assemblage, characterized by the co-occurrence of Paraisurus sp. aff. P. compressus, Cretoxyrhina vraconensis and Squalicorax teeth with strong serrations on the cutting edges. The tightly curved basal edge of the root in lateral teeth of C. vraconensis conforms to that of teeth from the Pawpaw Formation of Texas (M. rostratum Zone) and differs from the more divergent root lobes in younger specimens from the uppermost Albian and/or lowermost Cenomanian of Kolbay, Mangyshlak. Some specimens in the studied assemblage are probably older, within the range from the middle to earliest late late Albian. The strong numerical dominance of either Cretoxyrhina or Dwardius in late late Albian to early Cenomanian selachian faunas indicates competitive exclusion in these similar-sized, apex predatory sharks.Mikael Siversson* [mikael.siversson@museum.wa.gov.au], Department of Earth and Planetary Sciences, Western Australian Museum, 49 Kew Street, Welshpool, Western Australia 6106, Australia; Marcin Machalski [mach@twarda.pan.pl