Caseidae are an extinct family of basal synapsids that lived from the Late Carboniferous to Middle Permian between about 300 and 265 million years ago. Fossils of these animals come from the south-central part of the United States, from various parts of Europe, and possibly from South Africa if the genus Eunotosaurus is indeed a caseid as some authors proposed in 2021. Caseids show great taxonomic and morphological diversity. The most basal taxa were small insectivorous and omnivorous forms that lived mainly in the Upper Carboniferous and Lower Permian, such as Eocasea, Callibrachion, and Martensius. This type of caseid persists until the middle Permian with Phreatophasma and may be Eunotosaurus. During the early Permian, the clade is mainly represented by many species that adopted a herbivorous diet. Some have evolved into gigantic forms that can reach 6–7 metres (20–23 ft) in length, such as Cotylorhynchus hancocki and Alierasaurus ronchii, making them the largest Permian synapsids. Caseids are considered important components of early terrestrial ecosystems in vertebrate history because the numerous herbivorous species in this family are among the first terrestrial tetrapods to occupy the role of primary consumer. The caseids experienced a significant evolutionary radiation at the end of the early Permian, becoming, with the captorhinid eureptiles, the dominant herbivores of terrestrial ecosystems in place of the edaphosaurids and diadectids.
Ichniotherium is an ichnogenus of tetrapod footprints from between the Late Carboniferous period to the Early Permian period attributed to diadectomorph track-makers. These footprints are commonly found in Europe, and have also been identified in North America and Morocco. Three ichnospecies of Ichniotherium have been proposed as valid: I. cotta, I. sphaerodactylum, and I. praesidentis.
Palmichnium is an ichnofossil genus, interpreted as a eurypterid trackway. It has been found by many places around the world, such as Australia, Canada, United States and Wales.
Prorotodactylus is a dinosauromorph or pterosauromorph ichnogenus known from fossilized footprints found in Poland and France. The prints may have been made by a dinosauromorph that was a precursor to the dinosaurs, possibly closely related to Lagerpeton. Fossils of Prorotodactylus date back to the early Olenekian stage of the Early Triassic, making it the oldest known dinosauromorph. Its presence during this time extends the range of the dinosaur stem lineage to the start of the Early Triassic, soon after the Permian-Triassic extinction event. Prorotodactylus is the only ichnogenus within the ichnofamily Prorotodactylidae. Two ichnospecies are known, the type P. mirus and P. lutevensis.
Saurexallopus is an ichnogenus of four-toed theropod footprints from the Late Cretaceous period. The type ichnospecies is S. lovei, named and described in 1996 from the Harebell Formation. The taxon was originally named Exallopus, but later renamed as Saurexallopus as the former was preoccupied by a polychaete. A second species, S.zerbsti, was named and described in 2004 from the Lance Formation. In 2012 a four-toed track from the Cantwell Formation was referred to Saurexallopus indet. It was also suggested that Saurexallopus was produced by a therizinosaur taxon. In 2013 based on skeletal proportions it was suggested that the ichnotaxon was instead produced by an oviraptorosaur taxon. In 2014 a third species was named, S.cordata, from the Wapiti Formation. In 2018 several tracks from the Blackhawk Formation were referred to Saurexallopus indet.
The Tambach Formation is an Early Permian-age geologic formation in central Germany. It consists of red to brown-colored sedimentary rocks such as conglomerate, sandstone, and mudstone, and is the oldest portion of the Upper Rotliegend within the Thuringian Forest Basin.
The Sangre de Cristo Formation is a geologic formation in Colorado and New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian.
The Abo Formation is a geologic formation in New Mexico. It contains fossils characteristic of the Cisuralian epoch of the Permian period.
The Yeso Group is a group of geologic formations in New Mexico. It contains fossils characteristic of the Kungurian Age of the early Permian Period.
The 20th century in ichnology refers to advances made between the years 1900 and 1999 in the scientific study of trace fossils, the preserved record of the behavior and physiological processes of ancient life forms, especially fossil footprints. Significant fossil trackway discoveries began almost immediately after the start of the 20th century with the 1900 discovery at Ipolytarnoc, Hungary of a wide variety of bird and mammal footprints left behind during the early Miocene. Not long after, fossil Iguanodon footprints were discovered in Sussex, England, a discovery that probably served as the inspiration for Sir Arthur Conan Doyle's The Lost World.
Chelichnus is an ichnogenus of Permian tetrapod footprint. The name means tortoise traces, because the shape of the prints was originally mistakenly thought to be produced by a tortoise. This is now known to be incorrect, as tortoises did not evolve until much later. It was first found in Corncockle Quarry in Dumfries, Scotland, and described by Rev. Henry Duncan.
Limnopus is an ichnogenus of ancient tetrapod footprint. Its footprints have been found in Moscovian aged-rocks situated in Alveley, Shropshire, England, Colorado and West Virginia.
Gwyneddichnium is an ichnogenus from the Late Triassic of North America and Europe. It represents a form of reptile footprints and trackways, likely produced by small tanystropheids such as Tanytrachelos. Gwyneddichnium includes a single species, Gwyneddichnium major. Two other proposed species, G. elongatum and G. minore, are indistinguishable from G. major apart from their smaller size and minor taphonomic discrepancies. As a result, they are considered junior synonyms of G. major.
Protochirotherium, also known as Protocheirotherium, is a Late Permian?-Early Triassic ichnotaxon consisting of five-fingered (pentadactyl) footprints and whole tracks, discovered in Germany and later Morocco, Poland and possibly also Italy. The type ichnospecies is P. wolfhagenense, discovered by R. Kunz in 1999 alongside Chirotherium tracks, was named and described in 2004 and re-evaluated in 2007; a second ichnospecies, P. hauboldi, also exists, which was initially described as an ichnospecies of Brachychirotherium. Protochirotherium-like prints have also been documented from the Late Permian of Italy, possibly representing the oldest known fossils of mesaxonic archosauromorphs.
Rhynchosauroides is an ichnogenus, a form taxon based on footprints. The organism producing the footprints was likely a lepidosaur and may have been a sphenodont, an ancestor of the modern tuatara. The footprint consists of five digits, of which the fifth is shortened and the first highly shortened.
Amphisauropus is an amphibian ichnogenus commonly found in assemblages of ichnofossils dating to the Permian to Triassic. It has been found in Europe, Morocco, and North America.
Dimetropus is a reptile ichnogenus commonly found in assemblages of ichnofossils dating to the Permian to Triassic in Europe and North America. Analysis of trackways of Dimetropus provides evidence that the tracks were left by diadectids or non-therapsid synapsids ("pelycosaurs").
Batrachichnus is an amphibian ichnogenus commonly found in assemblages of ichnofossils dating to the Mississippian to Triassic of North America, South America, and Europe. The animal producing the tracks was likely a temnospondyl. B. slamandroides is the smallest known tetrapod footprint, produced by an animal with an estimated body length of just 8 millimeters (0.31 in)
Hyloidichnus is a reptile ichnogenus commonly found in assemblages of ichnofossils dating to the Permian to Triassic in North America, Africa, South America, and Europe.
Serpentichnus is a possible Permian trace fossil found in New Mexico, US. It takes the form of foot imprints separated by discontinuous groves interpreted as body imprints. It is attributed to early amphibians (Lysorophia) swimming near the bottom of a shallow body of water with a motion like that of a sidewinding snake.
