Mosasaur
Hainosaurus in a live reconstruction. This Tylosaurine from the Upper Cretaceous was up to 17 feet long.
- Europe ( Netherlands, Sweden)
- North America
- Africa
- Australia, New Zealand, Antarctica
The mosasaurs ( Mosasauridae, " Meuse lizard " ) were in the entire Upper Cretaceous a globally widespread group meeresbewohnender reptiles.
They are like the living snakes, lizards and amphisbaenians to Schuppenkriechtieren ( Squamata ), reaching up to 17 meters in length. Georges Cuvier recognized the fossil of mosasaur hoffmannii first time in the history of science, that the possibility of extinction of living beings consists.
- 6.1 Literature
- 6.2 Notes and references
- 6.3 External links
Features
The extremities of the mosasaurs had been formed as an adaptation to the aquatile life to fins, which similar to some other fossil marine reptiles the characteristics of the phenomenon of Hyperphalangie had (supernumerary phalanges ). The long tail in the end had a hypocerke fin, ie the end of the spine bends downward and supports the lower, larger part of the caudal fin. The elongated skull was equipped with a very powerful jaws. In the jaw of mosasaurs were mainly pointed, usually very similar teeth, but there were exceptions such as the genus globin Dens with spherical crushing teeth. In the middle mandible was a joint, which favored the opening of the mouth. Mosasaurs had many invertebrates that support together with the mostly 22 vertebrae and often more than 100 caudal vertebrae the body of the mosasaurs seven cervical vertebrae. The eyeball is a ring of thin plates of bone around these protected ( scleral ). Dark traces ( eumelanin ) show the fossil preserved soft tissue from Mosasaurierfossilien that they were dark in color and had a bright side of the abdomen.
As the ichthyosaurs and plesiosaurs are the mosasaurs have been able to maintain their body temperature at a constant high, the same level warm 35-39 ° C ( endothermic ).
Way of life
Nutrition
The teeth of mosasaurs suggests that mosasaurs specially fed on large nekton as larger fish. Fossil finds, physique and proportions of mosasaurs suggests that seabirds (then about Hesperornis ) and low-flying pterosaurs were eaten, as expected diverse marine reptiles were hunted by his mosasaurs ( probably mainly young animals), also ammonites. Based on current knowledge, they did not provide the prey rushing by, but killed them in rapid surprise attack. Some mosasaurs turned to other strategies in order to get other food. Thus, the representatives of the genus globin Dens broke on mussel beds from the mussels and ate them, similar to the much earlier existent and at this time only fossil preserved Placodontiden.
The mosasaurs could with pointy teeth, although violent attacks start, but could not with these teeth are crushed, the food, so the loot had to be completely swallowed. Through the joint in the lower jaw of the jaw could be opened very wide and include great food. Palate teeth were doing another.
Locomotion
Leave large limbs and the body proportions of mosasaurs suggests that mosasaurs swam quite agile. The main drive came here from the strong rudder tail. During an excavation in Jordan the fossil of a Prognathodongefunden that has a tail fin, with the longer part projecting downward instead of upward like most sharks. Was Mosasaurs could have swum faster with this tail than previously thought.
Reproduction
Since the findings of Mosasauriaembryos within the body of adult animals, it is considered safe, the mosasaurs, as the ichthyosaurs, were viviparous. 1996 Gordon Bell described the fragmented remains of a Plioplatecarpus, found in South Dakota, who recovered the bones of two embryos. Followed in 2001 by the description of Aigialosauriers Carsosaurus, in its rear part of the body were four well-developed embryo. The Agialosaurier are considered ancestors of Mosasauria or as their sister group. The location of the embryos showed that they were like whales and ichthyosaurs born with the tail first. Mosasauriaembryos were one to two meters long at birth. In the Niobrara Formation in Kansas a collection of very young mosasaurs was found whose fossil remains were deposited in an area ( Campanian to lower Coniacian ) more than 300 km was removed from the nearest coast of the Western Interior Seaway in their time. The animals have been so probably born on the open ocean.
History of research and fossil finds
Fossil evidence of intercontinental Mosasaurieren are known in great variety. The first discovery was in 1770 in a limestone building in Maastricht. By troops during the French Revolution, the found object came to Paris, where Georges Cuvier identified it as a lizard.
System
The closest relatives of mosasaurs are small and not so much adapted to a marine life Aigialosaurier, with whom they form the taxon Mosasauroidea. The Mosasauroidea are probably the extant monitor lizards very close and were a successful, but relatively short-lived side branch of the main line of the monitor lizards, which adapted itself to the marine life. A minority of scientists believes that the closer mosasaurs to snakes ( Serpentes ) are as related to monitor lizards, and called the taxon that snakes and mosasaurs united Pythonomorpha.
Within the more primitive mosasaurs Halisaurinae and the more advanced Natania be distinguished. Within the subfamily Mosasaurinae be found heavily modified forms, for example, a crushing dentition developed and how globin dens were Molluskenfressern specialized or Ichthyosaurierähnliche fish eaters, as Plotosaurus. The crocodile -like Goronyosaurus is isolated.
- Mosasauroidea Aigialosaurier
- Mosasaurs ( Mosasauridae ) Goronyosaurus
- Halisaurinae Eonatator
- Halisaurus
- Plesiotylosaurus, assignment controversial
- Prognathodon, assignment controversial
- Russelosaurina Ectenosaurus
- Tylosaurinae Hainosaurus
- Taniwhasaurus
- Tylosaurus
- Ectenosaurus
- Igdamanosaurus
- Platecarpus
- Plioplatecarpus
- Selmasaurus
- Yaguarasaurus
- Mosasaurus
- Plotosaurus
Etymology
The French-Belgian- Dutch river Meuse is called in Latin " Mosa ". The first fossils were found near this river, hence the scientific name Mosasauridae, so this means " Meuse lizard".