Coniophis

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Coniophis
Illustration of the holotype of Coniopsis precedens, from OC Marsh (chang.)

Illustration of the holotype of Coniopsis precedens ,
from OC Marsh (chang.)

Temporal occurrence
Upper Cretaceous ( Maastrichtian )
72 to 66 million years
Locations
Systematics
Scale lizards (Lepidosauria)
Scale reptiles (Squamata)
Toxicofera
Snakes i. w. S. (Ophidia)
Coniophidae
Coniophis
Scientific name of the  family
Coniophidae
Hoffstetter , 1955
Scientific name of the  genus
Coniophis
Marsh , 1892
Art
  • C. precedens Marsh, 1892

Coniophis is an extinct genus of snakes (Ophidia) from the late Cretaceous period . The only species thatdefinitely belonged to this genus, Coniophis precedens , was about 7 cm long and had snake-like teeth and body shape, as well as a skull with largely lizard-like bone structure. It was adapted to a burrowing way of life and probably ate small vertebrates . The fossil remains of Coniophis were first found at the end of the 19th century in the Lance Formation of the US state Wyoming anddescribedby Othniel Charles Marsh in1892. For a long time she was thought to be an early representative of the roller snakes . However, a revision published in 2012on the basis of additional fossil material identified Coniophis as the most original known snake, which compared to other genera had many primitive, but also some typical features of modern snakes. Anumber of other species have been describedfor the genus Coniophis . Their affiliation is, however, poorly established, mostly the original descriptions are based on only a few fossil eddies .

features

With an estimated maximum length of 7 cm, Coniophis was a comparatively short snake: The smallest snake living today , Tetracheilostoma carlae , reaches a body length of around 10 cm. The trunk of C. precedens was already typically snake-like in many ways. Based on their original position in the snake family tree, one can conclude that Coniophis, like “more modern” snakes, had hind legs. The skull of the genus, on the other hand, was still largely lizard-like and in many places had not developed the complex jaw suspension of today's snakes. However, with the long, pointed and recurved teeth, a similar dentition was present as with derived snakes.

The vertebral arches of Coniophis are flattened, a characteristic of burrowing ground dwellers. The vertebral arch joint was not formed by the articular processes (pre- and postzygapophyses), as is usual in other vertebrates, but solely by a forward-facing process (zygosphes) that is typical of snakes and fits into a rear depression (zygantrum) of the preceding vertebra. The vertebral canal has the three-pass shape typical of snakes. The joint bulbs are higher than wide and indented on the back. Unlike the representatives of the real snakes (Alethinophidia), they are not surrounded by a furrow. The anterior vertebrae are covered with very short hypapophyses (ventral appendages), the middle vertebrae instead have a pointed keel, while the posterior vertebrae have a rounded ventral surface. A caudal vertebra shows lymph apophyses , which serve to supply lymphatic hearts . Among scaly creepers , this is a feature of species with very long, narrow bodies, which suggests that Coniophis had a serpentine morphology.

The skull of Coniophis has only survived in fragments. The preserved teeth are tall, narrow, and curved backwards, resembling those of derived snakes. The tooth base is widened and partially has a slight notch. As is typical of all snakes, the teeth sit in shallow pits that are bordered by bone ridges. In contrast to the real snakes, the pits are open towards the mouth and the teeth are only weakly connected to the jawbone at the base. The mental foramen is enlarged, a common derivative characteristic of all snakes. In contrast to all other snakes, the maxilla towers above the premaxilla , which means that the foremost teeth cannot be folded out. In Coniophis, as in other basal snakes, the temporomandibular joint corresponded largely to that of today's lizards: The individual bones were relatively rigidly connected to one another, which is why the animals could not unhook their jaws. The morphology of the lower jaw, the front part of which was connected to the rear part like a rail, allowed them to slightly widen their mouths in order to swallow larger prey. The clearest synapomorphism with today's snakes is this increased mobility of the lower jaw bones to each other. Compared to the also Cretaceous and very original genus Najash and all other snakes, Coniophis lacks a tapered groove under the teeth. Due to the lack of material, the identification of original and derived features is problematic , especially in comparison with Najash .

Sites and fossil material

Shot of a wasteland
The Lance Formation in Wyoming , type locality of Coniophis precedens

The only safe to Coniophis belonging kind C. precedens , has so far only in the Lance Formation of the Powder River Basin in eastern US - State of Wyoming found. The Lance Formation is dated to the Maastrichtian , the youngest stage of the Upper Cretaceous (about 70-65 mya ). Overall, the recovered fossil material of C. precedens only includes vertebrae and fragments of the upper and lower jaw. It is unclear whether fossil snake vertebrae from the middle Paleocene ( Torrejonium ) can be assigned to the Tongue River Formation in Montana C. precedens . Although they cannot be distinguished externally from the Cretaceous eddies of the Lance Formation, there is a considerable period of time between them and the absence of skull elements does not yet allow a reliable determination.

Habitat and Ecology

The physique of Coniophis suggests that this genus lived burrowing; a way of life to which a flattened back and limb reduction are a common adaptation. The dentition is typical of carnivores that feed on small vertebrates. Such a diet suggests that Coniophis hunted above ground because this prey can only be easily captured above ground. The habitat of the animals consisted of the floodplain landscapes in the continental interior.

Systematics and taxonomy

The first remains of Coniophis , a series of vertebrae found in isolation, were found in the Lance Formation by an excavation team Othniel Charles Marshs in the late 19th century . Marsh described the genus in the American Journal of Science in 1892 along with other fossils using a single vortex (inventory number USNM 2143). He assigned them to the Ophidia and noted that, despite its age, the vertebra has all the characteristics of modern snakes. Marsh did not comment on the systematic classification. He announced a more detailed investigation in a later publication, but this never happened. The position of Coniophis within the Ophidia was unclear for a long time, mostly the genus was regarded as a representative or close relative of the roller snakes (Aniliidae). In 1955, Robert Hoffstetter established the monotypic family Coniophidae for the genus, which he classified as one of the burrowing branches of Henophidia . During the 20th and 21st centuries, numerous fossils were described as Coniophis species, coming from many different parts of the world and different geological series . Since these finds consist almost exclusively of eddies and extend over several hundred million years, it is extremely questionable whether they really belong to Coniophis . The list of fossils described as Coniophis is long and includes finds from the late Albian to the mid- Eocene . A final classification is not possible without a comprehensive revision.

  Ophidia  

 Coniophis


   

 Najash


  Serpentes  

 Blind snake-like (Scolecophidia)


   

 Dinilysia


   

 Matsoiidae


   

 Anilioidea


   

 Simolophiidae


   

 Macrostomata









Position of Coniophis within the snakes according to Longrich et al. 2012
Taxon author Year of description Age origin
C. carinatus *  pike 1959 middle Eocene United States
C. cosgriffi *  Armstrong Ziegler 1978 late campanium United States
C. dabiebus *  Rage & Werner 1999 Cenomanium Sudan
C. platycarinatus *  pike 1959 middle Eocene United States
C. precedens *  Marsh 1892 Maastrichtium United States
C. precedens Estes 1976 middle Paleocene United States
C. cf. precedens Fox 1975 late santonium / early campanium Canada
Coniophis sp. Rage 1988 Eocene France
Coniophis sp. albino 1991 Paleocene Brazil
Coniophis sp. Gardner & Cifelli 1999 outgoing albium / beginning cenomanium United States
Coniophis sp. Rage et al. 2004 Maastrichtium India
Coniophis sp. Augé & Rage 2006 late Paleocene Morocco
Coniophis sp. Augé & Rage 2006 early Eocene Morocco
Coniophis sp. Rage et al. 2010 middle Eocene France

In the first comprehensive revision of the genus, Nicholas Longrich, Bhart-Anjan Bhullar and Jacques Gauthier discarded all species except C. precedens in 2012 because they cannot be determined with certainty and, as a pure form taxon, may form a polyphyletic group. However, they do not rule out that the genus or related forms survived well beyond the Cretaceous period.

In fact, according to Longrich and colleagues , Coniophis was a " living fossil " as early as the late Cretaceous period , whose ancestor had separated from the common ancestor of the rest of the snakes around 70 million years earlier , as their phylogenetic analysis of the skeletal features suggests. Coniophis is the most primitive known representative of the snake; the next basal snake, Najash, lived in the Turonium, about 90 million years ago . During their existence, other early and at the same time much more modern snakes such as Sanajeh , Dinilysia or Euopodophis would have been contemporaries of the " ghost lineage " Coniophis .

literature

  • Adriana María Albino: Las serpientes de São José de Itaboraí (Edad Itaboraiense, Paleoceno medio), Brasil. In: Ameghiniana 27, 1991. pp. 337-342.
  • Sebastián Apesteguía, Hussam Zaher: A Cretaceous Terrestrial Snake with Robust Hindlimbs and a Sacrum. In: Nature 440, 2006. doi : 10.1038 / nature04413 , pp. 1037-1040.
  • Judy Gail Armstrong-Ziegler: An Aniliid Snake and Associated Vertebrates from the Campanian of New Mexico. In: Journal of Paleontology 52 (2), 1978. pp. 480-483.
  • Marc Augé, Jean-Claude Rage: Herpetofaunas from the Upper Paleocene and Lower Eocene of Morocco. In: Annales de Paléontologie 92, 2006. doi : 10.1016 / j.annpal.2005.09.001 , pp. 235-253.
  • Richard Estes: Middle Paleocene lower vertebrates from the Tongue River Formation, Southeastern Montana. In: Journal of Paleontology 50, 1976. pp. 500-520.
  • Richard C. Fox: Fossil Snakes from the Upper Milk River Formation (Upper Cretaceous), Alberta. In: Canadian Journal of Earth Sciences 12, 1975. pp. 1557-1563.
  • James D. Gardner, Richard L. Cifelli: A Primitive Snake from the Cretaceous of Utah. In: David M. Unwin (Ed.): Cretaceous Fossil Vertebrates. Special Papers in Palaeontology 60, London 1999. pp. 87-100.
  • Robert Hoffstetter: Squamates de Type Moderne. In: Jean Piveteau (Ed.): Traité de Paléontologie. Tome V. Masson, Paris 1955. pp. 606-662.
  • J. Alan Holman: Fossil Snakes of North America. origin, evolution, distribution, paleoecology. Indiana University Press, Bloomington 2000. ISBN 0-253-33721-6 .
  • Nicholas R. Longrich, Bhart-Anjan S. Bhullar, Jacques A. Gauthier: A Transitional Snake from the Late Cretaceous Period of North America. In: Nature 488, 2012. doi : 10.1038 / nature11227 , pp. 205-208, including supplementary material.
  • Othniel Charles Marsh: Notice of New Reptiles from the Laramie Formation. In: American Journal of Science, Series 3 43, 1892. pp. 449-453.
  • Max K. Hecht: Amphibians and reptiles. In: Paul Orman McGrew (Ed.): The Geology and Paleontology of the Elk Mountain and Tabernacle Butte Area, Wyoming. Bulletin of the American Museum of Natural History 117 (3), New York 1959. pp. 130–146 ( full text , complete volume)
  • Jean-Claude Rage: Le Gisement du Bretou (Phosphorites du Quercy, Tarn ‐ et ‐ Garonne, France) et Sa Faune de Vertebres de l'Eocene Superieur. In: Palaeontographica Department A 25, 1988. pp. 3-27.
  • Jean-Claude Rage, C. Werner: Mid ‐ Cretaceous (Cenomanian) Snakes from Wadi Abu Hashim, Sudan: The Earliest Snake Assemblage. In: Palaeontologia Africana 35, 1999. pp. 85-110 ( full text ).
  • Jean-Claude Rage, Guntupalli VR Prasad, Sunil Bajpai: Additional Snakes from the Uppermost Cretaceous (Maastrichtian) of India. In: Cretaceous Research 25, 2004. doi : 10.1016 / j.cretres.2004.02.003 , pp. 425-434.
  • Jean-Claude Rage, Marc Augé: Squamate Reptiles from the Middle Eocene of Lissieu (France). A Landmark in the Middle Eocene of Europe. In: Geobios 42, 2010. doi : 10.1016 / j.geobios.2009.08.002 , 253-268.

Web links

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

Individual evidence

  1. ↑ a b Hoffstetter 1955, p. 655.
  2. ↑ a b Marsh 1892, p. 450.
  3. ↑ Apesteguía & Zaher 2006, p. 2006.
  4. ↑ Longrich et al. 2012, pp. 205-206.
  5. ↑ Longrich et al. 2012, p. 206.
  6. ↑ Longrich et al. 2012, pp. 206-207.
  7. ↑ Longrich et al. 2012, suppl. mat. 2, p. 36.
  8. ↑ Longrich et al. 2012, suppl. mat. 1, pp. 1-3.
  9. ↑ a b Longrich et al. 2012, pp. 207-208.
  10. ↑ Longrich et al. 2012, p. 205.
  11. ↑ Holman 2000, pp. 28-32.
  12. ↑ a b Longrich et al. 2012, suppl. mat. 1, p. 6.
  13. ↑ Hecht 1959, pp. 138-139.
  14. ↑ Armstrong-Ziegler 1978, pp. 80-83.
  15. ↑ Rage & Werner 1999, pp. 449-453.
  16. ↑ Hecht 1959, p. 139.
  17. ↑ Estes 1976, p. 512.
  18. ↑ Fox 1975, pp. 1558-1560.
  19. ↑ Albino 1991, pp. 337-338.
  20. ↑ Gardner & Cifelli 1999, pp. 91-93.
  21. ↑ Rage et al. 2004, 428-429.
  22. ↑ Augé & Rage 2006a, p. 247.
  23. ↑ Augé & Rage 2006a, pp. 249-250.
  24. ↑ Rage et al. 2010, p. 259.
This version was added to the list of articles worth reading on December 15, 2012 .