Varanopidae

Varanops brevirostris, live reconstruction

• North America
• Russia
• South Africa

The Varanopidae, sometimes Varanopseidae, are a group synapsider land vertebrates, which are included in the group of Pelycosaurier. There were relatively small, carnivorous or insectivorous animals that reminded externally to monitor lizards.

Features

The skull of Varanopidae was built elongated and slightly, the eyes were rather the back of the head and the lower jaw was narrow and long. The teeth of these animals were approximately uniformly ( homodont ), sharp and slightly curved backwards. The rest of the body was also slightly built and had slender limbs and a long tail on.

The Varanopidae were rather small animals and included probably the fastest predators of their time. Varanodontine representatives of Varanopidae as Varanops could reach a maximum length of 1.5 to 2 meters. Myctosaurine genera were smaller. The appearance strongly resembled modern lizards, without the two groups were related. Varanopidae probably ate meat, possibly by insects or fish.

Occurrence and distribution

The Varanopidae first appeared in the Carboniferous of North America and arrived in Perm a nearly worldwide distribution, later finds are also well known from Russia. The oldest representative is Archaeovenator hamiltonensis, recent fossils close Mesenosaurus Romeri and Pyozia mesenensis from Russia and Elliotsmithia longiceps and Heleosaurus scholtzi from South Africa. Thus also the Varanopidae have the longest temporal extent of all Paleozoic synapsids. Elliotsmithia, whose remains were found in South Africa, is the only well-preserved Pelycosaurier, which was found in Gondwana.

The relative rarity of Varanopidae in the fossil record can be determined by Reisz and Modesto explained as follows: Although they are a relatively rare component of the Permian terrestrial vertebrate communities, sets the available fossil record close but that the Varanopseida had a long and varied history. The rare fossil tradition, by the nature of the deposit, have remained where terrestrial Vertebratengemeinschaften get fossil, are explained. With the exception of the deposits in Bromacker in the Thuringian Forest and Richard Spurs in Oklahoma all sites of the lower Permian represent different faunal communities of the lowlands that were either aquatic or were near water. These included lake and pond deposits or deposits of floodplains and flood plains. Thus handed down in such deposits primarily vertebrates that lived near the water in the lowlands. In higher Fossil societies Varanopidae with different taxa, however, are often represented. So the Dolese mine in Richard Spurs contains two representatives of the smaller Myctosaurinen also the great Varanopiden Varanops. Since the vertebrates are generally smaller at higher elevations habitats occupied the Varanopidae in the ecosystem, the ecological niche of top predators.

By the end of the Permian - age the Varanopidae are extinct.

System

Among the most important representatives of this group included:

• Archaeovenator, Upper Carboniferous, North America
• Aerosaurus, Upper Carboniferous and Lower Permian, North America
• Apsisaurus, Permian, North America
• Varanosaurus, Permian, North America
• Mycterosaurus, mid- Permian, North America
• Heleosaurus, Middle Permian, South Africa
• Pyozia, medium Perm, Russia
• Mesenosaurus, Permian, Russia
• Varanodon, Permian, North America
• Varanops, Permian, North America
• Elliotsmithia, Late Permian, South Africa

Systematically form the Varanopidae the basalsten representatives of Eupelycosauria from which later the therapsids ( " mammal-like reptiles " ), and finally developed the mammals have. However, this classification is not without controversy, as some are considered developed watched groups like the Ophiacodontidae appear in the fossil record earlier than the Varanopseiden. The similarity of the Varanopidae with today's dragons in the past led to incorrect classifications frequently among others of Mesenosaurus, Archaeovenator and Apsisaurus as Diapsiden.

Paleoecology

The Varanopidae were small, agile hunters. Interestingly, among the vast majority of contemporary therapsids from South Africa many large meat and herbivores. Accordingly, the Varanopidae seem to have successfully set up in a specialized niche, like her time extensive occurrence in the fossil record shows. At higher altitudes, the Varanopidae occupied the role of top predators, while the niche occupied the small predator in the lowlands near the water where larger synapside robbers were present. The only predators from the Permian of South Africa of comparable size was Youngina capensis. However, this had neither the long and slender limbs nor the serrated dentition, which was typical of the Varanopidae. Youngina is also narrated from the Late Permian, while Heleosaurus and Elliotsmithia were mittelpermische forms. In the Permian deposits of northern Russia to find the fossils of the genus diapsiden Lanthanolania, which reached a size comparable to the Varanopidae. Differences in the dentition suggest, however, that Lanthanolania and representatives of Varanopidae occupied different ecological niches.

There is evidence that some species of Varanopidae took care of their young. So you found in South Africa, the well-preserved remains of five individuals of Heleosaurus - a full-grown animal and 4 pups of the same size - close together. This is the oldest evidence of parental care in amniotes and Pelycosauriern at all, about 140 million years before this could be detected in the dinosaur genera Psittacosaurus and Oryctodromeus. Brood care was an enormous survival advantage in a Paleozoic environment that was dominated by therapsids.