Spinosauridae

Spinosauridae
Skeletal reconstruction of Spinosaurus
Temporal occurrence
Lower to Upper Cretaceous ( Barremium to Cenomanium )
130.7 to 93.9 million years
Locations
Europe Africa South America Asia
Systematics
Ornithodira Dinosaur (dinosauria) Lizard dinosaur (Saurischia) Theropoda Spinosauroidea Spinosauridae
Scientific name
Spinosauridae
Stromer , 1915

The Spinosauridae ("prickly lizards") are a group of large carnivorous dinosaurs . The different species have been found in Australia, Europe, North Africa and North America. The type species, the Spinosaurus described in 1915 , is characterized by long spines on its back, which are extensions of the vertebrae and probably had to carry a back sail; The entire family owes its name to this feature. Today, various fossils from Africa, Asia, Europe and South America are assigned to the Spinosauridae.

features

A special feature of this group are the spiky appendages of the dorsal vertebrae, which were probably surrounded by skin, such as in Dimetrodon . These skin sails were up to 1.5 meters high. Furthermore, these dinosaurs had a crocodile-like head and an elongated body. The teeth were narrow, pointed and not very jagged, and the muzzle long and flat.

Function of the processes of the vertebrae

There are different opinions regarding the function of the vertebral processes. A connection with the heat regulation is often assumed. It is assumed that the appendages were surrounded by a skin sail with blood vessels. With its help, the Spinosauridae could possibly regulate their body temperature and would have been cold-blooded animals . The Spinosauridae could, however, also belong to the warm-blooded animals ; in this case the sail would have protected against overheating. Similar to African elephants through their ears, the Spinosauridae could have given off excess heat through the sail.

As a further possible function of the sail, they could have presented it to enemies, rivals or potential sexual partners and thus have a deterrent or stimulating effect on them.

Systematics

Sereno et al. presented a phylogenetic tree of the Spinosauridae at the first description of Suchomimus tenerensis in 1998 , which divided them into the two subfamilies Spinosaurinae and Baryonychinae . Accordingly, Irritator and Spinosaurus represent sister taxa. This representation was confirmed by dal Sasso et al. 2006.

According to this, Suchomimus and Baryonyx , whose only representative Baronyx walkeri was described in England in 1986, represent the Barynoychinae, while Irritator and Spinosaurus were compared to these as Spinosaurinae. Sasso et al. add the Cristatusaurus lapparenti described in 1998 to the Baryonychinae , which in the original description by Sereno et al. was not yet described. As a sister group of the entire Spinosauridae, the Torvosauridae with the genera Torvosaurus and Eustreptospondylus are named, but today they are assigned to the Megalosauridae .

Spinosauroidea	Spinosauridae     Spinosaurinae    Spinosaurus      Irritator (synonymous with Angaturama limai )      Oxalaia      Siamosaurus      Vallibonavenatrix   Baryonychinae    Ichthyovenator      Baryonyx      Suchomimus      Megalosauridae

Live reconstruction of Baryonyx as a fish hunter

This family tree is justified primarily by features of the skull morphology, since this part of the skeleton is at least partially present in most species. The Spinosauroidea are primarily justified by the formation of the strong front limbs with a sickle-like thumb claw. The extension of the snout region by a parallel extension of both the maxillary and premaxillary , the specific design of the outer nasal cavity and the formation of a secondary roof of the mouth are very weighty apomorphies that secure the monophyly of the Spinosauridae to specialize in fishing . In the Spinosaurinae there was a reduction in the number of teeth on premaxillaria and maxillaria with an associated increase in tooth spacing and the almost straight alignment of the teeth, which were present in both Irritator and Spinosaurus . Compared to Irritator, Spinosaurus is mainly justified by the strong enlargement of the dorsal processes of the spine and the resulting dorsal sail - what this looked like in the Irritator is not known.

The Altispinax , which is only described on the basis of a tooth, is now regarded as the noun dubium ; there are no more detailed systematic data on Siamosaurus . The validity of Cristatusaurus is also questioned .

Web links

Commons : Spinosauridae  - Collection of images, videos and audio files

supporting documents

1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , pp. 87-88, online .
2. ↑ Fossils in Australia - Spinosaur bones shake theories. Mirror online .
3. ↑ ^{a b} Stefano Maugeri, Silvio Bruno, Maria Luisa Bozzi: Dinosaurs: facts, scientific knowledge and new unsolved puzzles ; Final edition: 2001, Neuer Kaiser Verlag; Pp. 179-182
4. ↑ Steven Parker: Dinosaurs ; 2004, Weltbild publishing group; ISBN 3-8289-6031-6 , p. 199
5. ↑ ^{a b c} Paul C. Sereno , Allison L. Beck, Didier B. Dutheil, Boubacar Gado, Hans CE Larsson, Gabrielle H. Lyon, Jonathan D. Marcot, Oliver WM Rauhut , Rudyard W. Sadleir, Christian A. Sidor, David D. Varricchio, Gregory P. Wilson, Jeffrey A. Wilson: A Long-Snouted Predatory Dinosaur from Africa and the Evolution of Spinosaurids. In: Science . Vol. 282, No. 5392, 1998, pp. 1298-1302, doi: 10.1126 / science.282.5392.1298 , digital version (PDF; 475 kB) .
6. ↑ Cristiano Dal Sasso , Simone Maganuco, Eric Buffetaut , Marco A. Mendez: New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities. In: Journal of Vertebrate Paleontology. Vol. 25, No. 4, 2005, ISSN  0272-4634 , pp. 888-896, doi : 10.1671 / 0272-4634 (2005) 025 [0888: NIOTSO] 2.0.CO; 2 .
7. ^ Alan J. Charig , Angela C. Milner: Baryonyx, a remarkable new theropod dinosaur. In: Nature . Vol. 324, No. 6095, 1986, pp. 359-361, doi: 10.1038 / 324359a0 .
8. ^ Philippe Taquet , Dale A. Russell : New data on spinosaurid dinosaurs from the Early Cretaceous of the Sahara. In: Comptes Rendus de l'Académie des Sciences. Series IIA: Earth and Planetary Science. Vol. 327, No. 5, 1998, pp. 347-353, doi: 10.1016 / S1251-8050 (98) 80054-2 .
9. ↑ David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 .
10. ↑ Elisabete Malafaia, José Miguel Gasulla, Fernando Escaso, Iván Narváez, José Luis Sanz and Francisco Ortega. 2019. A New Spinosaurid Theropod (Dinosauria: Megalosauroidea) from the late Barremian of Vallibona, Spain: Implications for Spinosaurid Diversity in the Early Cretaceous of the Iberian Peninsula. Cretaceous Research. DOI: 10.1016 / j.cretres.2019.104221
11. ↑ Ronan Allain, Tiengkham Xaisanavong, Philippe Richir, Bounsou Khentavong: The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the early cretaceous of Laos. In: Natural Sciences . Vol. 99, No. 5, 2012, pp. 369-377, doi: 10.1007 / s00114-012-0911-7 .