Gatunek typowy
Guizhoudella triangularis Wang et Wang, 1978 from the Late Famennian of Daihua Formation at Daihua, Guizhou, China.

Opis

Ramiform elements of the apparatus with surface granular in places; denticles fused into wide, denticulated blades.
Most elements of the apparatus of Guizhoudella dinodontoides are homeomorphic with those of Dinodus leptus Cooper, 1939. In the Tournaisian samples of the latter species delicate ramiform S and M elements co-occur with closely similar P2 elements (Elictognathus) that have been suggested to belong to the Siphonodella apparatus. The only species of ‘Siphonodella’ which could be matched with these sets of non-P1 elements in the material studied by myself is ‘S.’ lobata. The Famennian species is so similar to that from the Tournaisian that its independent origin is difficult to accept. The problem thus emerges how the ‘Elictognathus’ and ‘Siphonodella’ elements originated, if they truly belonged to the same apparatus. It has to be noted that in Dinodus no tuberculation of Guizhoudella (or Playfordia) type occurs. Instead, the elements show distinct imprints of ameloblasts.
‘Elsonella’ rhenana Lindström et Ziegler, 1965 from the latest Givetian hermanni-cristatus Zone differs from G. dinodontoides only in a low-angle arrangement of processes in the probable S1 element. This suggests that the stratigraphic distribution of the Famennian Guizhoudella species reflects their evolution, in which the apparatus became gradually disorganized, with increased variability and irregular appearance of elements. It would then depart from the Dinodus-like morphology. The long-lasting Guizhoudella species lineage appears to be cryptic for most of its range.

Synonimy

Zasięg czasowy

Literatura