Ankylosauridae

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Ankylosauridae
Euoplocephalus

Euoplocephalus

Temporal occurrence
Upper Jurassic to Upper Cretaceous ( Kimmeridgian to Maastrichtian )
157.3 to 66 million years
Locations
  • Worldwide?
Systematics
Dinosaur (dinosauria)
Pelvic dinosaur (Ornithischia)
Thyreophora
Eurypoda
Ankylosaurs (ankylosauria)
Ankylosauridae
Scientific name
Ankylosauridae
Brown , 1908

The Ankylosauridae are one of the two subtaxa (subgroups) into which the Ankylosauria dinosaur group is divided. They lived from the Upper Jurassic to the Upper Cretaceous .

features

The Ankylosauridae share the body structure of the Ankylosauria. The broad, massive trunk is supported by four short, strong limbs, with the hind legs longer than the front legs. The neck, torso, and top of the tail were covered with armor made of bone plates.

The skull of the Ankylosauridae was - in contrast to the Nodosauridae , the second subgroup, wider and roughly triangular in shape. The two bony outgrowths behind the eye socket and on the cheek were large and pyramidal - in the Nodosauridae they were more rounded and blunt. As with all ankylosauria, the teeth were small and leaf-shaped and adapted to a plant-based diet. The top of the skull and sometimes even the eyelids were also provided with bony armor.

In contrast to the Nodosauridae, the Ankylosauridae had no conspicuous spines in the shoulder region . There are also differences in the construction of the shoulder blade , which in the Ankylosauridae did not have the bump-like outgrowth ( acromion ). Another distinguishing feature is the bony tail lobe, which was present at least in the more highly developed Ankylosauridae in the Upper Cretaceous. The oldest Ankylosauridae in the Upper Jurassic and the Lower Lower Cretaceous initially had flexible tails without a tail, which could be bent to the side in an S-shape. In the Upper Lower Cretaceous and during the Lower Upper Cretaceous the tails stiffened more and more. In the last 20 million years of the Upper Cretaceous the tail club was added.

Paleobiology

Model of the tail of an Ankylosauridae with a clearly recognizable tail lobe

The wide mouth suggests that the Ankylosauridae were not specialized in certain plant forms, but rather plucked everything at random. The tail lobe probably served as a defense against predators, according to other opinions it could also have been used in rival fights with conspecifics or, according to a dubious theory, served as bait that distracted attackers from the head. In many respects the presumed way of life of the Ankylosauridae agrees with that of the other Ankylosauria.

Systematics

The systematics of the ankylosauria is controversial in many areas. This is also due to the fact that many finds are poorly preserved and a clear diagnosis is often hardly possible. Also under discussion is the membership of the Polacanthidae or Polacanthinae , which are sometimes assigned to the Ankylosauridae and sometimes to the Nodosauridae. The system described here largely follows M. Vickaryous et al. (2004), for comparison - where there are deviations - the system of K. Carpenter or the assignment by the person who first described it is shown in brackets after the name. (See also Internal Systematics of Ankylosauria .)

literature

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, pp. 226-235, ISBN 978-0-691-13720-9 , online .
  2. ^ Victoria Arbor & Philip Currie. Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features. Journal of Anatomy, Aug 21, 2015; doi: 10.1111 / joa.12363
  3. ↑ Clifford A. Miles, Clark J. Miles: Skull of Minotaurasaurus ramachandrani, a new Cretaceous ankylosaur from the Gobi Desert. In: Current Science. Vol. 96, No. 1, 2009, ISSN  0011-3891 , pp. 65-70, digital version (PDF; 1.04 MB) .
  4. ↑ Victoria M. Arbor, Michael E. Burns, Robert M. Sullivan, Spencer G. Lucas, Amanda K. Cantrell, Joshua Fry, Thomas L. Suazo. A New Ankylosaurid Dinosaur from the Upper Cretaceous (Kirtlandian) of New Mexico with Implications for Ankylosaurid Diversity in the Upper Cretaceous of Western North America. PLoS ONE , 2014; 9 (9): e108804 DOI: 10.1371 / journal.pone.0108804
  5. ^ JP Wiersma & RB Irmis. 2018. A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. Et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA. PeerJ 6: e5016; doi: 10.7717 / peerj.5016
  6. ↑ Victoria M. Arbor, Philip J. Currie and Demchig Badamgarav. 2014. The Ankylosaurid Dinosaurs of the Upper Cretaceous Baruungoyot and Nemegt formations of Mongolia. Zoological Journal of the Linnean Society, Volume 172, Issue 3, pages 631–652, November 2014, DOI: 10.1111 / zoj.12185
  7. ↑ Victoria M. Arbor and David C. Evans. 2017. A New Ankylosaurine Dinosaur from the Judith River Formation of Montana, USA, Based On An Exceptional Skeleton with Soft Tissue Preservation. Royal Society Open Science. DOI: 10.1098 / rsos.161086

Web links

Commons : Ankylosauridae  - collection of images, videos and audio files