The first known specimen of Ursquilla (MNHN R. 62691) was discovered in Nahal Tze'elim (formerly known as the Ouadi Seiyal Valley), Israel near a road leading from Beersheba to Mount Sodom, likely in the vicinity of Arad, and is kept in the National Museum of Natural History, France.
The deposits in which it originates are part of the Campanian-aged Chert Member of the Mishash Formation, and cover the southeastern flank of the anticline of the Judaean Mountains.
[1] In 1969, it was published in the Treatise on Invertebrate Paleontology that Martin Glaessner stated the Eryon yehoachi type specimen is not a carapace, but actually represents the telson and part of the sixth abdominal segment of a mantis shrimp.
The other two specimens are preserved together in the same slab (BMNH I 7316) found in the outcrops of the Amman Formation east of Al-Karak, Jordan, presented in May 1906 and kept in the London Natural History Museum.
An epoxy resin cast of the type specimen is also kept in the London Natural History Museum and labelled as BMNH I 15472.
[3] A fifth specimen was found by Stan Natkaniec in the Negev Desert, Israel during a private trip and donated to the State Museum of Natural History Stuttgart.
The submedian keels are straight and show a gradual increase in height down the animal's length before abruptly ending at the hind margin of the segment.
[3] Halfway between the frontmost pair of protrusions and the front margin of the telson is a crease known as the prelateral lobe (a feature seen in derived squilloid mantis shrimp).
[3] SMNS 67703 shows possibly up to 11 backward-pointing articulated spines along the outer margin of the proximal part of the exopod.
[5] This result was further supported by the later discovery of an additional Ursquilla specimen, revealing a prelateral lobe on the telson like that found in other squillids.
[4] A phylogenetic analysis conducted by Smith et al. (2023) recovered Squillidae as a non-monophyletic grouping, with Nodosculda (traditionally placed in Sculdidae) being the closest relative to Squilla mantis despite the latter and Ursquilla having previously been assigned to the same family.
However, it is also proposed that such an unconventional result may be due to the fact that Ursquilla, Nodosculda and Lysiosquilla nkporoensis are poorly known, and more material of squillids is needed to resolve the relationships of the group.
Archaeocaris vermiformis Archaeocaris graffhami †Bairdops elegans Perimecturus parki Perimecturus rapax †Bairdops beargulchensis †Daidal pattoni †Daidal schoellmanni †Daidal acanthocercus Gorgonophontes fraiponti Gorgonophontes peleron †Chabardella spinosa †Tyrannophontes theridion †Tyrannophontes gigantion †Triassosculda ahyongi †Tyrannosculda laurae †Pseudosculda laevis †Archaeosculda phoenicia †Sculda pennata †Sculda syriaca †Ursquilla yehoachi †Lysiosquilla nkporoensis †Nodosculda fisherorum Squilla mantis
[3] However, it was later pointed out by Haug et al. (2013) that since the two Jordanian specimens are preserved close together on the same slab but oriented in different directions, tectonic deformation would not cause them both to be elongated the same way.