Whip Scorpions, Uropygi, are a highly distinctive group of Arachnids with large claws, robust, heavily sclerotized bodies and a long whip-like, post-abdominal flagellum, as well as the ability to squirt an offensive, vinegar-like liquid as a defence mechanism. There are about 126 extant species of Whip Scorpions, as well as eleven described fossil species, with the oldest coming from the Carboniferous.
Camel Spiders, Solifugae, are large, Spider-like Arachnids, lacking the ability to produce silk, and having extremely enlarged chelicerae (fangs) and leg-like pedipalps which are held above the ground when moving. There are about 1209 extant species of Camel Spider, but only six known fossil species, the oldest of which again comes from the Carboniferous.
The Crato Formation outcrops on the northern flanks of the Chapada do Araripe, a plateau on the border between Ceará, Pernambuco andPiauí States in northern Brazil. In is noted for its exceptionally well-preserved fossils, which include Dinosaurs, Crocodiles, Fish, Pterosaurs, Crustaceans, Arachnids, Plants and most notably Insects, which are present in large numbers, often showing exceptional preservation. These Insects are of particular interest as they date from a time in the Early Cretaceous when Flowering Plants were rapidly diversifying, and relationships between Insect and Plant groups that would come to dominate the Earth’s terrestrial biology were being formed.
In a paper published in the journal PeerJ on 3 January 2024, William Santana, Allysson Pinheiro, Thiago Andrade Silva and Daniel Lima of the Museu de Paleontologia Plácido Cidade Nuvens at the Universidade Regional do Cariri describe a new species of Whip Scorpion from the Crato Formation, as well as a new specimen of the Crato Camel Spider Cratosolpuga wunderlichi.
The new Whip Scorpion species is placed in the genus Mesoproctus, and given the specific name rayoli in honour of Rafael Ribeiro Rayol a Brazilian federal attorney, who helped, along with the Brazilian Federal Police, helped recover a significant amount of fossil material from the Crato which was being smuggled out of the country (an ongoing problem for Brazilian palaeontology), including the specimens from which the species is described, as part of 'Operation Santana Raptor'.
Mesoproctus rayoli is described from two specimens, both recovered by Operation Santana Raptor the first of which is complete an measures 65.9 mm in length, while the second is incomplete, preserving only the forepart of the body. A third specimen in the collection of the Museum für Naturkunde Berlin, is also assigned to the species. This specimen was described as Mesoproctus sp. in 2002 in a paper by Jason Dunlop of the Museum für Naturkunde Berlin and David Martill of the University of Portsmouth, who collected the specimen legally in the 1990s.
The genus Mesoproctus was first designated by Jason Dunlop in 1998 to describe Mesoproctus rowlandi, from a single Crato specimen held in the collection of the Ulster Museum. The specimen described by Dunlop and Martill as Mesoproctus sp was substantially larger than the only known specimen of Mesoproctus rowlandiI, and neither were very well preserved, making it impossible for Dunlop and Martill to be sure that this was not an older specimen of the same species. The better preservation of Santana et al.'s specimens enables them to be confident that they do have a separate specimen, and that the Museum für Naturkunde Berlin specimen belongs to this.
Santana et al. also describe a new specimen of Cratosolpuga wunderlichi, a Camel Spider first described in 1996 by Paul Seldon, then of the University of Manchester and William Shear of Hampden-Sydney College, to describe a specimen from the Crato held by a private collector in Germany. Several other specimens of this species have subsequently been described, however, Santana et al.'s specimen shows several features which have not been seen before, including a styliform flagellum with a bulbous base on the chelicera, a structure present only in adult males. The specimen was collected at Santana do Cariri in Ceará State, Brazil, and donated to the Museu de Paleontologia Plácido Cidade Nuvens via the Projeto Força Tarefa, which encourages local children to collect and contribute fossils to the museum.
The new Arachnid specimens described by Sanatana et al. provide further insight into the nature of the Early Cretaceous Crato environment. They note that Whip Scorpions and Camel Spiders both favour arid environments, as do a number of other Arthropods and Plants found in these deposits. The theory that the Crato may have been arid is further supported by the presence of salt pseudomorphs and gypsum beds, which tend to form around hypersaline bodies of water in arid environments.
The study also emphasises the importance of both good law enforcement and community engagement programs in preserving the geological and palaeontological heritage of Brazil, and keeping material from important deposits such as Crato within the country, where they can be studied by local scientists and interpreted within the context of the environment where they were found.
See also...
Online courses in Palaeontology.
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