Nemegtosauridae

Nemegtosauridae
Live reconstruction of the head of Nemegtosaurus
Temporal occurrence
Lower Cretaceous ( Aptian ) to Upper Cretaceous ( Maastrichtian )
126.3 to 66 million years
Locations
Asia Africa South America
Systematics
Lizard dinosaur (Saurischia) Sauropods (Sauropoda) Macronaria Titanosauriformes Titanosauria Nemegtosauridae
Scientific name
Nemegtosauridae
Barrett & Upchurch , 1995

Systematic position of Tapuiasaurus and the Nemegtosauridae within the sauropods. From Zaher and colleagues, 2011.

The Nemegtosauridae are a group of sauropod dinosaurs within the Titanosauria . While it originally only included the genera Nemegtosaurus and Quaesitosaurus , other genera have recently been assigned to it - these assignments, however, vary depending on the author. The validity of the Nemegtosauridae is not generally accepted, so the name is not used by many researchers. As a group of derived (advanced) Titanosauria, the Nemegtosauridae are often compared to the Saltasauridae , another derived Titanosauria group that includes Saltasaurus and Opisthocoelicaudia , for example .

Research history

The taxon Nemegtosauridae was established in 1995 by Barrett and Upchurch to summarize the genera Nemegtosaurus and Quaesitosaurus . Both genera are known only from skulls, the morphology of which shows strong similarities with that of the Diplodocoidea . In fact, the Nemegtosauridae was initially classified together with all other titanosaurs within the Diplodocoidea. It was not until Salgado and colleagues (1997) and Wilson and Sereno (1998) showed that titanosaurs were actually more closely related to Brachiosaurus- like forms. Although both studies suggested that the Nemegtosauridae should also be classified within or as relatives of the titanosaurs, some other researchers maintained a classification within the Diplodocoidea. For example, Upchurch and colleagues (2004) list the Nemegtosauridae as representatives of the Diplodocoidea, while they place the Titanosauria in closer relation to the Brachiosaurus -like forms. With the discovery of Rapetosaurus , a titanosaur became known for the first time, from which complete skull material has been preserved in connection with the residual skeleton: This discovery shows that titanosaurs actually had a diplodocoid-like skull. This skull shape must therefore have developed independently of each other in Diplodocoids and Titanosaurs ( convergent evolution ). Today the classification of the Nemegtosauridae within the Titanosauria is generally accepted consensus .

Definition and commonly derived features

The first definition of the group comes from Upchurch and colleagues (2004), who classified the Nemegtosauridae within the Diplodocoidea: According to these authors, the Nemegtosauridae is a stem line-based taxon ( steam-based definition ) that includes all taxa that are closer to Nemegtosaurus than were related to Diplodocus . Wilson (2005) sees the Nemegtosauridae as representatives of the Titanosauria and changed the definition: The Nemegtosauridae are a stem line-based taxon that includes all taxa that were more closely related to Nemegtosaurus than to Saltasaurus . Wilson also suggested various jointly derived features ( synapomorphies ), which should differentiate the group from other groups: For example, the tear bone (lacrimal) showed a process on the front; furthermore, the tooth crowns had a thin cross-section. The teeth of the dental had a smaller diameter than those of the intermaxillary bone ( premaxillary) and the upper jaw (maxillary), as in Diplodocus .

Genera

While the group originally only included Nemegtosaurus and Quaesitosaurus , other genera have been assigned to the group to this day. Wilson (2005) states that at least Rapetosaurus should also be assigned to the group . He lists other genera as possible further Nemegtosaurids, including Opisthocoelicaudia , Antarctosaurus wichmannianus , cf. "Antarctosaurus" septentrionalis , Mongolosaurus , Phuwiangosaurus and Bonitasaura . Zaher and colleagues (2011) also attribute the newly discovered genus Tapuiasaurus to the Nemegtosauridae.

Web links

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

Individual evidence

1. ↑ ^{a b c} Hussam Zaher, Diego Pol, Alberto B. Carvalho, Paulo M. Nascimento, Claudio Riccomini, Peter Larson, Rubén Juarez-Valieri, Ricardo Pires-Domingues, Nelson Jorge da Silva Jr., Diógenes de Almeida Campos: A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians. In: PLoS ONE . Vol. 6, No. 2, 2011, e16663, doi : 10.1371 / journal.pone.0016663 .
2. ↑ ^{a b} Paul Sereno : Nemegtosauridae. (No longer available online.) In: Taxon Search. Archived from the original on July 17, 2011 ; Retrieved August 29, 2014 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
3. ↑ ^{a b c d} Jeffrey A. Wilson: Redescription of the Mongolian Sauropod Nemegtosaurus mongoliensis Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous Sauropod diversity. In: Journal of Systematic Palaeontology. Vol. 3, No. 3, 2005, ISSN  1477-2019 , pp. 283-318, doi : 10.1017 / S1477201905001628 .
4. ↑ Leonardo Salgado , Jorge Orlando Calvo : Evolution of Titanosaurid Sauropods. II: The cranial evidence. In: Ameghiniana . Vol. 34, No. 1, 1997, pp. 33-48, online .
5. ↑ Jeffrey A. Wilson, Paul C. Sereno: Early Evolution and Higher-level Phylogeny of Sauropod Dinosaurs (= Journal of Vertebrate Paleontology. Vol. 18, Supplement to No. 2 = Society of Vertebrate Paleontology. Memoir. Vol. 5, ISSN  1062-161X ). Society of Vertebrate Paleontology, Chicago IL 1998, doi : 10.1080 / 02724634.1998.10011115 .
6. ^ Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: 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 , pp. 259-324.
7. ↑ Kristina Curry Rogers: Titanosauria: A Phylogenetic Overview. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. 2005, ISBN 0-520-24623-3 , pp. 50-103, doi : 10.1525 / california / 9780520246232.003.0003 .