The pineal gland is a small endocrine gland in the brain of most vertebrates. In the darkness the pineal gland produces melatonin, a serotonin-derived hormone, which modulates sleep patterns following the diurnal cycles. The shape of the gland resembles a pine cone, which gives it its name. The pineal gland is located in the epithalamus, near the center of the brain, between the two hemispheres, tucked in a groove where the two halves of the thalamus join. It is one of the neuroendocrine secretory circumventricular organs in which capillaries are mostly permeable to solutes in the blood.
The Varanidae are a family of lizards in the superfamily Varanoidea and order Anguimorpha. The family, a group of carnivorous and frugivorous lizards, includes the living genus Varanus and a number of extinct genera more closely related to Varanus than to the earless monitor lizard (Lanthanotus). Varanus includes the Komodo dragon, crocodile monitor, savannah monitor, the goannas of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the earless monitor lizard and chinese crocodile lizard. The oldest members of the family are known from the Late Cretaceous of Mongolia.
Monitor lizards are lizards in the genus Varanus, the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recognized.
Megalania is an extinct species of giant monitor lizard, part of the megafaunal assemblage that inhabited Australia during the Pleistocene. It is the largest terrestrial lizard known to have existed, reaching an estimated length of 3.5 to 7 metres, and weighing between 97–1,940 kg (214–4,277 lb), but the fragmentary nature of known remains make estimates highly uncertain.
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation. The hole in the head which contains the eye is known as a pineal foramen or parietal foramen, since it is often enclosed by the parietal bones.
Peltosaurus is an extinct genus of anguid lizard from North America that lived from the Eocene to the Oligocene. Peltosaurus belongs to the anguid subfamily Glyptosaurinae. The type species Peltosaurus granulosus was named in 1873 by American paleontologist Edward Drinker Cope. Many additional species have been named, but most have been reassigned to different genera. For example, Peltosaurus piger, named in 1928, was reclassified as Odaxosaurus piger, and P. jepseni, named in 1942 from the Paleocene of Wyoming, but was later reclassified as Proxestops jepseni. In 1955 a new species, Peltosaurus macrodon, was named from the Eocene of California. Lizard bones from the Late Miocene of Nebraska were attributed to a new species of Peltosaurus called P. minimus in 1976, extending the fossil range of Peltosaurus and Glyptosaurinae into the Neogene. However, these bones were later referred to a genus of skinks called Eumeces, meaning that the fossil range of Peltosaurus and Glyptosaurinae does not go beyond the Paleogene.
Mastodonsaurus is an extinct genus of temnospondyl from the Middle Triassic of Europe. It belongs to a Triassic group of temnospondyls called Capitosauria, characterized by their large body size and presumably aquatic lifestyles. Mastodonsaurus remains one of the largest amphibians known, and may have exceeded 6 meters in length.
Charles Whitney Gilmore was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum. Gilmore named many dinosaurs in North America and Mongolia, including the Cretaceous sauropod Alamosaurus, Alectrosaurus, Archaeornithomimus, Bactrosaurus, Brachyceratops, Chirostenotes, Mongolosaurus, Parrosaurus, Pinacosaurus, Styracosaurus ovatus and Thescelosaurus.
Paroodectes is an extinct genus of placental mammals from clade Carnivoraformes, that lived in Europe during the middle Eocene.
Tsoabichi is an extinct genus of caimanine crocodylian. Fossils are known from the Green River Formation in Wyoming, and date back to the Ypresian stage of the Eocene. The genus was named and described in 2010 by paleontologist Christopher A. Brochu, with the type species being Tsoabichi greenriverensis. According to the current understanding of caiman evolutionary relationships, Tsoabichi is a basal member of Caimaninae and may have evolved after caimans dispersed into North America from northern and central South America, their main center of diversity in the Cenozoic.
Telmasaurus is an extinct genus of varanoid lizard from the Late Cretaceous of Mongolia. Fossils have been found from the Djadokha and Barun Goyot Formations that date between the early and middle Campanian stage from approximately 80 to 75 million years ago. The type species Telmasaurus grangeri was named in 1943.
Bahndwivici is an extinct genus of lizard known from a nearly complete and articulated skeleton discovered in rocks of the Green River Formation of Wyoming, United States. The skeleton is very similar to that of the modern Chinese crocodile lizard, Shinisaurus.
Shinisauria is a clade or evolutionary grouping of anguimorph lizards that includes the living Chinese crocodile lizard Shinisaurus and several of its closest extinct relatives. Shinisauria was named in 2008 by Jack Lee Conrad as a stem-based taxon to include all anguimorphs more closely related to Shinisaurus than to Anguis fragilis, Heloderma suspectum or Varanus varius. Several recent phylogenetic analyses of lizard evolutionary relationships place Shinisauria in a basal position within the clade Platynota, which also includes monitor lizards, helodermatids, and the extinct mosasaurs. Shinisaurians were once thought to be closely related to the genus Xenosaurus, but they are now considered distant relatives within Anguimorpha. The fossil record of shinisaurians extends back to the Early Cretaceous with Dalinghosaurus, which is from the Aptian aged Yixian Formation of China. Two other extinct shinisaurians are currently known: Bahndwivici from the Eocene of Wyoming and Merkurosaurus from the Late Oligocene of Germany and the Early Miocene of the Czech Republic. An indeterminate shinisaurian is known from an isolated tail found in the Eocene aged Messel pit in Germany.
Babibasiliscus is an extinct genus of casquehead lizard that lived in what is now Wyoming during the early Eocene, approximately 48 million years ago. The genus is known from a single species, Babibasiliscus alxi, which was named by paleontologist Jack Conrad in 2015 on the basis of a fossilized skull from the Bridger Formation in the Green River Basin. The name Babibasiliscus comes from the Shoshoni word babi, meaning "older male cousin", and Basiliscus, a modern-day genus of casquehead lizards. The specimen is undeformed and nearly complete except for the tip of the snout and the top of the skull, making it unclear whether the distinctive bony crest of living corytophanids was present in prehistoric relatives like Babibasiliscus. The skull is about 42 millimetres (2 in) in length and the entire body is estimated to have been about 0.6 metres (2 ft) long. Bones on the right side of lower jaw of the specimen are thickened and fused together, suggesting that the jaw had broken and healed when the animal was alive.
Geiseltaliellus is an extinct genus of iguanian lizards that lived in what is now western Europe during the Eocene. It belongs to the family Corytophanidae, which includes modern casquehead lizards. Many fossils are known from Germany, France, and Belgium, with the most well preserved coming from the Messel pit lagerstätte in Messel, Germany. German paleontologist Oskar Kuhn named the genus in 1944 after the Geiseltal valley where the first specimens were found, designating the type species Geiseltaliellus longicaudus. Three new species — G. louisi, G. lamandini, and G. grisolli — were named in the 1990s and 2000s on the basis of more fragmentary remains from France and Belgium, although G. louisi has since been synonymized with G. longicaudus. In 2009 the Messel pit specimens were recognized as belonging to a species distinct from that of the G. longicaudus specimens in Geiseltalt and were collectively reclassified under a new name, G. maarius.
Palaeovaranidae, formerly known as Necrosauridae, is an extinct clade of anguimorph lizards known from the Paleogene of Europe. They have sometimes been recovered as members of Varanoidea. It contains three genera.
Paranecrosaurus is an extinct genus of lizard from the Eocene Messel Pits of Germany. It contains a single species, Paranecrosaurus feisti, originally described as a species of Saniwa. It was carnivorous, as indicated by the presence of the lizard Cryptolacerta as stomatch contents. It is placed in the family Palaeovaranidae.
Archaeovaranus is genus of varanid lizard from the early Eocene (Ypresian) Yuhuangding Formation of Hubei Province, China. The genus contains a single species, Archaeovaranus lii, known from a nearly complete skeleton. The holotype, which includes an intact skull, is associated but disarticulated. Archaeovaranus fills a gap in the varanid fossil record, as it represents a stem-varanid from the early Eocene of East Asia, and is the closest known relative of Varanus.
This is an overview of the paleofauna of the Eocene Messel Formation as explored by the Messel Pit excavations in Germany. A former quarry and now UNESCO World Heritage Site, the Messel Formation preserves what once were a series of anoxic lakes surrounded by a sub-tropical rainforest during the Middle Eocene, approximately 47 Ma.
