44-4 And They Were Roommates: Multiple Ichnotaxa Within Irregular Echinoid Tests (Macraster) From The Lower Cretaceous of Texas, USA

Session: Paleontology, Paleoecology/Taphonomy, Phylogenic Morphological Patterns (Posters)

Presenting Author:

Authors:

Abstract:

The ichnology of burrows within echinoid tests is poorly understood in the fossil record; this paper will explore and describe a new occurrence of feeding burrows within irregular echinoid  (Macraster sp.) tests from the Lower Cretaceous Fort Worth Formation of Texas. We have recorded the ichnotaxa Planolites isp., P. beverleyensis, P. montanus, and Arachnostega gastrochaenae in six irregular echinoid specimens, two of which contain both ichnotaxa. This ichnofauna represents the highest diversity of burrows known from echinoid test interiors. The burrows present show that the sediment infill was likely nutrient rich, and used as a food source as the organisms moved along the interface between infilling sediment and the interior surface of test plates. The morphology of these burrows shows a tiered structure, with Arachnostega occupying a shallower tier than the Planolites, closer to the sediment infill/test boundary. The presence of burrows within these tests is only detectable where the tests have been damaged, suggesting that such occurrences are probably more common than suggested by the current literature. These specimens show that the presence of burrows within echinoid tests is very likely under-reported and serves to highlight the importance of “poorly preserved” material in the fossil record.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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