Starfish first appeared in the fossil record in the Cambrian. The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups. Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays. Despite this, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds". By the late Paleozoic, the crinoids and blastoids were the predominant echinoderms, and some limestones from this period are made almost entirely from fragments from these groups. In the two major extinction events that occurred during the late
Spiny softshell turtle Spiny softshell turtle The spiny softshell turtle ("Apalone spinifera") is a species of softshell turtle, one of the largest freshwater turtle species in North America. Both the common name, spiny softshell, and the specific name, "spinifera" (spine-bearing), refer to the spiny, cone-like projections on the leading edge of the carapace, which are not scutes (scales). The spiny softshell turtle’s scientific name is very descriptive of the animal. “Apalone” comes from the Greek word “apalos” meaning soft or tender, and “spinifera” is of Latin descent; “spina-“ referring to thorn or spine and “-ifer” meaning bearing. This species is a member of