Lametasaurus

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Lametasaurus
Temporal occurrence
Upper Cretaceous ( Maastrichtian )
72 to 66 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Theropoda
Ceratosauria
Abelisauridae
Lametasaurus
Scientific name
Lametasaurus
Matley , 1924
Art
  • Lametasaurus indicus

Lametasaurus is a possible, dubious genus of dinosaurs from the Upper Cretaceous ( Maastrichtian ) India . It was described in 1924 by Charles Matley using pelvic bones, a shin and skin bone plates (osteoderms), which come from the Lameta formation of Bara Simla , a hill in Madhya Pradesh, central India . This find is lost today. Initially the genus was described as a representative of the Stegosauridae ; Later, however, it turned out that the find was made up of remains from various species ( chimera ): It includes the bones of a theropod and osteoderms, which are believed to have come from sauropods and crocodiles . The pelvic bones and the tibia are nowascribed tothe Abelisauridae , a group of theropods within the Ceratosauria .

The name Lametasaurus ("Lameta"; Gr. Sauros - "lizard") refers to the Lameta Formation , the rock unit from which the fossils originate.

Research history

The fossils were recovered in 1917 by Charles Matley from the so-called "carnosaur beds" of Bara Simla. In a preliminary examination of the material, Matley found that some scaly, prickly and plate-like osteoderms can be ascribed to a theropod from the Carnosauria group , and referred to Ceratosaurus , of which osteoderms are also known. After the remaining fossils were dissected, however, Matley recognized the bones of a stegosaurid (an armored dinosaur) - a sacrum , both iliac bones and a left shinbone (tibia). He concluded that the osteoderms can also be assigned to this stegosaurid. In 1924, based on these findings, he described the new genus Lametasaurus and considered it a close relative of the stegosaurid Omosaurus - so these fossils were considered the first definitive evidence of an armored dinosaur from Asia. Matley and Friedrich von Huene later suspected that the neck of this genus was armored with osteoderms arranged in rings. They interpreted a large osteoderm later discovered by Barnum Brown as a tail lobe, similar to that known from Ankylosaurus . Based on these osteoderms, these researchers now classified Lametasaurus as a member of the Nodosauridae .

In 1935, Dhirendra Kishore Chakravarti came to the conclusion that the pelvic bones and the shin bone could neither be assigned to a relative of Omosaurus nor to a nodosaurid, but rather come from a megalosaurid theropod. This researcher points out clear differences to Stegosaurus , Omosaurus and Nodosaurus ; for example, the sacrum is relatively much longer and not flattened vertically. The osteoderms could not definitely be assigned to an armored dinosaur; some would possibly also be from theropods. In contrast, this researcher attributed some large bone plates to crocodiles. The supposed tail lobe is now classified as the osteoderm of a titanosaur .

features

Compared to other Ceratosauria, the shin was relatively short and robust, similar to Majungasaurus , but different from Aucasaurus and Xenotarsosaurus . The iliac bone may have had a particularly wide brevis shelf , a bone process that serves as an attachment point for the tail muscles.

validity

The validity of the genus Lametasaurus is considered dubious, usually it is classified as the noun dubium (naked name). Lametasaurus is only the first of more than half a dozen genera of the Abelisauridae that were described from the Lameta Formation. Since the bones were rarely found in context, but mostly isolated, and since a large part of these fossils has been lost today, these genera cannot be differentiated from one another in a meaningful way. For example, the bone material described as Lametasaurus , Coeluroides , Dryptosauroides , Indosuchus , Indosaurus , Ornithomimoides mobilis, and Rajasaurus probably belonged to only one or two different genera.

Individual evidence

  1. ^ A b Charles A. Matley: Note on an armored dinosaur from the Lameta beds of Jubbulpore. In: Records of the Geological Survey of India. Vol. 55, No. 2, 1924, ISSN  0370-5226 , pp. 105-109 ( online ( memento of the original from September 30, 2016 in the Internet Archive ) 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 note. ). @1@ 2Template: Webachiv / IABot / www.dli.ernet.in
  2. ^ A b c Matthew T. Carrano, Scott D. Sampson: The Phylogeny of Ceratosauria (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. Vol. 6, No. 2, 2008, ISSN  1477-2019 , pp. 183-236, doi : 10.1017 / S1477201907002246 .
  3. ^ A b Timothy B. Rowe , Jacques Gauthier : Ceratosauria. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . University of California Press, Berkeley CA et al. 1990, ISBN 0-520-06726-6 , pp. 151-168.
  4. ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide. Archived from the original on July 10, 2011 ; accessed on August 7, 2014 .
  5. ^ Charles A. Matley: On the stratigraphy, fossils and geological relationships of the Lameta beds of Jubbulpore. In: Records of the Geological Survey of India. Vol. 53, No. 2, 1921, pp. 142-169.
  6. ↑ Friedrich Baron von Huene , Charles Alfred Matley: The Cretaceous Saurischia and Ornithischia of the Central Provinces of India (= Geological Survey of India. Palaeontologia Indica. NS Vol. 21, No. 1, ISSN  0970-0528 ). Manager of Publication, Delhi 1933.
  7. ↑ a b Dhirendra Kishore Chakravarti: Is Lametasaurus indicus an armored dinosaur? In: American Journal of Science. Series 5, Vol. 30, No. 176, August 1935, ISSN  0002-9599 , pp. 138-141, doi : 10.2475 / ajs.s5-30.176.138 .
  8. ^ Donald F. Glut : Dinosaurs. The Encyclopedia. McFarland & Company, Jefferson NC et al. 1997, ISBN 0-89950-917-7 .
  9. ↑ a b Michael D. D'Emic, Jeffrey A. Wilson, Sankar Chatterjee : The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India. In: Journal of Vertebrate Paleontology. Vol. 29, No. 1, 2009, ISSN  0272-4634 , pp. 165-177, doi : 10.1671 / 039.029.0131 .
  10. ^ Rubén D. Juárez Valieri, Juan D. Porfiri, Jorge O. Calvo : New Information on Ekrixinatosaurus novasi Calvo et al 2004, a giant and massively-constructed Abelisauroid from the "Middle Cretaceous" of Patagonia. In: Jorge Calvo, Juan Porfiri, Bernardo González Riga, Domenica Dos Santos (eds.): Paleontología y Dinosaurios desde América Latina. (= Series Documentos y Testimonios. Aportes. No. 24). EDIUNC, Mendoza 2011, ISBN 978-950-39-0265-3 , pp. 161–169, digitized version (PDF; 643.51 kB) ( Memento of the original from March 16, 2012 in the Internet Archive ) Info: The archive link was automatically used and not yet tested. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.notosoft.com.ar
  11. ↑ Ronald S. Tykoski, Timothy Rowe: Ceratosauria. 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. 47-70.