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Variety of Glen Rose Fm. Echinoid Spines
 

Variety of Glen Rose Fm. Echinoid Spines



Update: Since I originally posted this image I now have fairly positive identifications for three of these and a good guess on the fourth.  From top to bottom:  The knurled large spine is Paracidaris? texanus (Whitney & Kellum) one of two known cidarids in the formation; The second is Pseudodiadema aguileria (Maldonado) and is recognized by its triangular cross section; The third is the unknown. It looks like spines on some Goniopygus but there are no large Goniopygus in this strata.  It is more likely a scrobicular spine (https://www.nhm.ac.uk/our-science/data/echinoid-directory/taxa/glossary.jsp?begins=S&showImageID=164) from one of the cudarids, either Paracidaris or Balanocidaris;  fourth is the spine of the Echinothurids of which we seem to only find plates and these rare tiny spines. They are known to have the reverse taper and a hoof-like distal end.  Note that Bill Thompson (2016) has put the name Echinothuria mccallae on these but there are no known articulated specimens and his erection of this name is IMHO sketchy at best.  

 

All were collected by me at the same location from the echinoid marker bed (AKA microzone) at the base of Unit 2, Lower Member, Glen Rose Formation, Trinity Group (Albian) Comal County, Texas

From the album:

Texas Echinoids, ERose

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