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
Ferreira's spiny tree-rat Ferreira's spiny tree-rat Ferreira's spiny tree-rat, "Mesomys hispidus", is a spiny rat species from South America. It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela. The etymology of the species name corresponds to the Latin word "" meaning "bristly". The description of "Mesomys hispidus" was conducted on a specimen collected by the naturalist Alexandre Rodrigues Ferreira during his travels in Amazonian Brazil, hence the species name. Initially deposited in the Museu Real d'Ajuda of Portugal, it has been brought to Paris in 1808 after the plundering of Lisbon by the armies of Napoleon. Then,