Anapsida

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Anapsida

Obsolete systematic group

The taxon dealt with here is not part of the systematics presented in the German-language Wikipedia. More information can be found in the article text.

Systematics
Sub-stem : Vertebrates (vertebrata)
Superclass : Jaw mouths (Gnathostomata)
Row : Land vertebrates (Tetrapoda)
without rank: Amniotes (Amniota)
without rank: Sauropsida
Obsolete taxon :
Subclass : Anapsida
Substantially replaced by the concept of Parareptilia , not least due to the inclusion of the turtles in the Diapsiden
Scientific name
Anapsida
Williston , 1917
Schematic representation of the amniotic skull types , some of which are still systematically important today : A =  anapsid , B =  synapsid , C =  diapsid .

According to the traditional view, the Anapsida are a subclass of reptiles whose nominal characteristic is the anapsid skull, i.e. a skull without a skull or temporal window in the cheek or temple region (tempora). According to the classic Anapsida concept, the non-possession of temple windows is an indication of a closer relationship between the turtles and a number of certain fossil terrestrial vertebrates of the Permian and Triassic , which also have an anapsid skull.

Although there was no question that the anapsid skull was an original feature of the terrestrial vertebrates and therefore not well suited for characterizing one of their systematic subgroups, the established group term anapsida was initially retained in the recent past. More modern, cladist-based concepts defined the Anapsida as the basal monophylum of the amniotes , which includes the turtles and their closest fossil relatives, whereby different investigators came to different results with regard to the composition of this clade. However, since a less basal position of the turtles is now considered likely, the group term anapsida is used less and less in current scientific literature.

etymology

Anapsida is a compound from α privativum and the Greek word ἁψίς ( apsis , "arch", "vault"), which together means "bowless". It indirectly refers to the lack of temporal or temple windows in the representatives of this group. Temporal windows are typical of the skulls of certain other amniotic groups and are partially delimited by relatively narrow bone bridges, the temporal, temporal or zygomatic arches. Since anapsids have no temporal windows, they consequently also have no temporal arches and are therefore "bowless".

Classic concept

Skull of a subadult sea turtle (family Cheloniidae, Testudines) without premaxillary . The windowless temple region is clearly visible. The indentation in the posterior side wall of the skull is the tympanic cavity (Cavum tympani).
The anapside skull of Captorhinus aguti (family Captorhinidae, Eureptilia) from the Lower Permian of North Texas in the Paleontological Museum in Munich.
The anapside skull of Scutosaurus karpinskii (family Pareiasauridae, Parareptilia) from the Upper Permian of the European part of Russia in the Paris Natural History Museum.
The windowless skull and the reptile-like anatomy of Diadectes (family Diadectidae, basal Reptiliomorpha), here in the American Museum of Natural History in New York, tempted early paleontologists to classify this genus as the Anapsida and to consider it as an ancestral form of the turtle .

After Henry Osborn proposed the division of reptiles into Diapsida and Synapsida in 1903 , which was primarily based on the formation of the temporal region of the skull, Samuel Williston published an article in 1917 in which, on the same principle as Osborn, he divided the reptilia into recommended four main groups: Anapsida , Synapsida , Diapsida, and Parapsida . The Anapsida were primarily defined by the complete absence of temporal windows and contained the turtles and a number of fossil, reptile-like terrestrial vertebrates, which at that time were summarized under the term Cotylosauria . This conception of the Anapsida essentially existed until the second half of the 20th century, when the cotylosaur concept was later abandoned, and some authors outsourced the turtles as a separate subclass closely related to the Anapsida, so that the Anapsida was now a collective group for everyone as "cotylosaurs" but now considered as real reptiles formed groups.

Cladistic concept

In the second half of the 20th century, and especially from the 1990s, the investigation of the relationships between living things was increasingly carried out using cladistic methods . This change also had an impact on the biological system , as the organisms were now divided into groups strictly according to the relationship hypotheses. This also had an impact on the anapsida concept. Among other things, the classic concept of "Reptilia" was discarded, because according to this, the reptiles are not a natural family group ( Monophylum ), but a Paraphylum , because mammals and birds, descendants of land vertebrates traditionally grouped under "Reptilia", were not included. Therefore, the classic concept of Reptilia has been replaced by the concept of Amniota.

Monophyletic groups with a basal position within the amniota, which the turtles contained, were now called anapsida. Since different processors came to different results in their analyzes, the composition and position of the Anapsida fluctuated relatively strongly. In addition to the turtles, they once contained the captorhinids and another time a number of basal amniotes, which were and are also summarized under the term parareptiles . Despite such differences, these clades still agreed to a certain extent with the traditional conception of the anapsids, because both the captorhinids and most parareptiles have anapsic skulls and were classified among the cotylosaurs at the time. The name Anapsida for these clades was justified.

However, recent studies of the relationship between the turtles have shown that the turtle line does not change shortly after the synapsid and sauropsid lines have separated from the sauropsid line (reptiles in the modern, cladistic understanding, including birds; group also known as Reptilia) split off, but later. The closest fossil relatives of the turtles would therefore be neither parareptiles nor captorhinids, but a group within the diapsids. In such a scenario, the group term anapsida is in fact no longer justified and due to the growing acceptance of the diapsid hypothesis among biologists and paleontologists in the recent past, it is disappearing from the scientific literature.

Systematics

Classic concept

According to Williston (1925):

1Groups contain representatives who are now considered to be basal Reptiliomorpha , that is, the main group representatives of the amniotes.
2The captorhinids are basic representatives of the eureptiles , the sister taxon of the parareptiles .
3Groups contain non-amniotic, "higher" tetrapods, which were later summarized under the term microsauria and assigned to the lepospondyli .
4th Groups contain representatives who are now classified as parareptiles.
5 Sauravus , the eponymous taxon of the Sauravidae, is now considered a non-amniotic, "higher" tetrapod from the group of Nectridea , a subgroup of the Lepospondyli.

According to Kuhn (1958):

1Groups contain representatives who are now considered to be basal Reptiliomorpha , that is, the main group representatives of the amniotes.
2Groups contain representatives who are now classified as parareptiles .
3Group contains representatives who today e.g. T. at the base of the Eureptilia (e.g. Captorhinidae ) and z. T. are considered to be basal reptiliomorpha (e.g. Limnoscelis )
4thThe microsaurs are higher, non-amniotic tetrapods, are now considered paraphyletic and are associated with the lepospondyli .

According to Carroll (1988):

According to Carroll (1988), the turtles form their own subclass.

1 The protorothyrid (id) ae are now regarded as paraphyletic and placed at the base of the eureptiles.
2The captorhinids are basic representatives of the eureptiles , the sister taxon of the parareptiles .
3 Batropetes , the nominal genus of the Batropetidae, is now considered a non-amniotic, "higher" tetrapod from the group of microsauria , a subgroup of the Lepospondyli, which is presumably paraphyletic.
4th Groups contain representatives who are now classified as parareptiles.

Cladistic concept

According to Gauthier et al. (1988):

  Amniota  

 Synapsida including mammals


   
  Parareptiles  

 † Mesosauridae


   

 † Procolophonia


   

 † Millerettidae


   

 † Pareiasauria





  Reptilia *  
  Anapsida  

 † Captorhinidae


   

 Turtles (Testudines)



  Romeriida  

 † Paleothyris


  Diapsida  

 † Araeoscelidia


   

 Sauria including all other recent reptiles and birds







According to Modesto (2000):

  Amniota  

 Synapsida including mammals


  Reptilia *  
  Anapsida  

 † Mesosauridae


   

 † Millerettidae


   

 † Eunotosaurus


   

 † Pareiasauria


   

 † Procolophonidae


   

 Turtles (Testudines)







  Eureptilia  

 † Captorhinidae


   

 † Paleothyris


   

 Diapsida including all recent reptiles and birds






*here in the cladistic sense, synonymous with the taxon Sauropsida

Individual evidence

  1. ^ Henry F. Osborn: On the primary division of the Reptilia into two subclasses, Synapsida and Diapsida. Science. Volume 17, No. 424, 1903, pp. 275-276, doi: 10.1126 / science.17.424.275-b (Note: the first publication of the taxon names Diapsida and Synapsida, February 1903).
  2. ^ Henry F. Osborn: The reptilian subclasses Diapsida and Synapsida and the early history of the Diaptosauria. In: Memoirs of the American Museum of Natural History , Volume 1, No. 8, 1903, pp. 451-507, hdl: 2246/5739 (note: an extensive follow-up to the Science article, November 1903).
  3. ^ Samuel W. Williston: The Phylogeny and Classification of Reptiles. In: The Journal of Geology. Vol. 25, No. 5, 1917, pp. 411-421, JSTOR 30062555 .
  4. ↑ a b Oskar Kuhn: amphibians and crawling animals of the past (= Die Neue Brehm-Bücherei. Issue 217). 2nd, unchanged edition, reprint of the 1st edition from 1958. Westarp-Wissenschaften, Hohenwarsleben 2004, ISBN 3-89432-663-8 .
  5. ^ A b Robert L. Carroll: Vertebrate Paleontology and Evolution. WH Freeman and Co., New York 1988, ISBN 0-7167-1822-7 , p. 615.
  6. ^ Edwin H. Colbert: The Age of Reptiles. Dover Publications, Mineola NY 1997 (expanded and revised new edition of the original work from 1965), ISBN 0-486-29377-7 , p. 223.
  7. ^ A b Jacques A. Gauthier, Arnold G. Kluge, Timothy Rowe: The early evolution of the Amniota. In: Michael J. Benton (Ed.): The phylogeny and classification of the tetrapods. Volume 1: Amphibians, reptiles, birds. Systematics Association Special Volume. No. 35A, 1988, pp. 103-155.
  8. ↑ a b Sean P. Modesto: Eunotosaurus africanus and the Gondwanan Ancestry of Anapsid Reptiles. In: Palaeontologia africana , Volume 36, 2000, ISSN  0078-8554 , pp. 15-20.
  9. ↑ Rafael Zardoya, Axel Meyer: The evolutionary position of turtles revised. Natural sciences. Vol. 88, No. 5, 2001, pp. 193-200, doi: 10.1007 / s001140100228 .
  10. ^ Samuel W. Williston, The Osteology of the Reptiles. Harvard University Press, Cambridge MA 1925, doi: 10.5962 / bhl.title.45170 .

Web links

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