Largest Utah Beckwithia Aglaspid Ever Discovered

Beckwithia typa

Phylum Arthropoda, Stem-group Chelicerata, Order Aglaspidida (Aglaspida)

Geologic Time: Upper Middle Cambrian

Size (25.4 mm = 1 inch): Beckwithia fossil is 6 ¼” in length on a 12 ½ x 5 x 1 5/8” plate

Fossil Site: Weeks Formation, House Range, Utah

Code: PFT525

Price: Sold


Beckwithia typa Aglaspid FossilDescription: Only few select specialist collectors and scientists are aware of this magnificent Beckwithia. It has been available for sale since about 2006. However the asking price had been eight thousand dollars. Quite a hefty price for this problematic specimen, now substantially lowered. To the best of our knowledge, it is the largest Beckwithia yet discovered. It is a positive and negative specimen. The preservation is spectacular. It is fully 3D, has good color and the body shows minute detail. Notice the pustulate skin. The tail spine is fully displayed. Yes, obviously, there is one big problem. The plate upon which the Beckwithia is found was unfortunately sheared off at the quarry site. Somewhere in that quarry, or on somones backyard patio paving stone, sits forlornly, the left side of the cephalon. (Yes, the Week's quarry produces patio and walkway paving stone!).

The Aglaspida (Aglaspids) are an unranked (incertae sedis) clade of early arthropods that due to their resemblance to horseshoe crabs were once believed to ancestral horseshoe crabs, and were included with the chelicerata. Most recently, aglaspids are held to be distinct group, possibly closely related trilobites, The older idea that they link trilobites within Chelicerata is no longer predominant. Although aglaspid fossils are distributed worldwide, they are relatively rare in the fossil record. They are, in fact, one of the largest non-trilobite arthropod groups in the fossil record. Aglaspids had 8 to 12 pairs of appendages and a prominent telson. These morphological characteristics have caused considerable support for Aglaspids being the maker of Protichnites ichnofossils. Protichnites of the Upper Cambrian Mount Simon Sandstone in Wisconsin have been suggested as the first footprints on land in the fossil record, possibly marking the transition to terrestrial life that took tens of millions years more to complete.

Please excuse my poor photos. The true color is somewhere in between the darker and lighter shots.

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