Aulacognathus angulatus Bischoff, 1986

Waid, Christopher B. T. & Cramer, Bradley D., 2017, Telychian (Llandovery, Silurian) conodonts from the LaPorte City Formation of eastern Iowa, USA (East-Central Iowa Basin) and their implications for global Telychian conodont biostratigraphic correlation, Palaeontologia Electronica 42 (6), pp. 1-37 : 22

publication ID

https://doi.org/ 10.26879/685

persistent identifier

https://treatment.plazi.org/id/BD71879D-676D-FFCC-5FCF-27BEF5EFFE80

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Felipe

scientific name

Aulacognathus angulatus Bischoff, 1986
status

 

Aulacognathus angulatus Bischoff, 1986

Figures 8.20 View FIGURE 8 , 9.9-9.10 View FIGURE 9

*1986 Aulacognathus angulatus ; Bischoff, pl. 3, figs. 15-24 (P 1 and P 2 elements)

Description. P 1 element consists of a blade with two anteriorly oriented lateral processes that intersect the blade at nearly the same point. Blade denticulate. Anterior portion of the blade bowed. Posterior portion curved and slightly deflected outwardly. Lateral processes narrow, with aligned nodes. A small, very steep platform is developed between the lateral processes and the blade. P 2 element angulate. Posterior process deflected inwardly. White matter distributed almost to the base of the element on both the anterior and posterior processes. S 1/2? element alate, with arched, excavated, and thickly-walled basal cavity. Denticles are widely separated and oval shaped in cross section. White matter extends below denticles in near-rectangles and is separated by translucent material.

Remarks. This rare species has been previously recovered only from an unnamed limestone unit in New South Wales, Australia ( Bischoff, 1986, p. 9, locality number 9). Bischoff assigned the unit to the Stimulograptus sedgwickii or Spirograptus turriculatus graptolite biozones, which correlate to the upper Aeronian to lower Telychian ( Cramer et al., 2011). Our specimens were recorded with conodonts from the lower Telychian Pt. eopennatus Superzone.

Material examined. One S 1/2, one P 2, one P 1 element.

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