Onchopristis

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Onchopristis
Onchopristis numidus (living reconstruction)

Onchopristis numidus (living reconstruction)

Temporal occurrence
Barremium to Cenomanium
130.7 to 93.9 million years
Locations
  • worldwide
Systematics
Chordates (chordata)
Cartilaginous fish (Chondrichthyes)
Stingray (batoidea)
Sclerorhynchiformes
Sclerorhynchidae
Onchopristis
Scientific name
Onchopristis
Stromer , 1917
species
  • Onchopristis numidus ( Haug , 1905)
  • Onchopristis dunklei McNulty & Slaughter , 1962

Onchopristis is a genus of the extinct, saw-ray-like family of the Sclerorhynchidae . Onchopristis fossilsare found in Africa, Europe, Asia, North and South America in deposits from the Lower Cretaceous ( Barremium ) to the Lowest Upper Cretaceous ( Cenomanium ).

Etymology and history of research

The first description of the type species was carried out in 1905 by Émile Haug under the name Gigantichthys numidus . The genus Gigantichthys established by Wilhelm Dames in 1887 with the type species Gigantichthys pharao was recognized as being identical to the genus Onchosaurus described by Paul Gervais in 1852 . Since Ernst Stromer von Reichenbach saw in Gigantichthys numidus significant differences to Gigantichthys pharao , he did not put the former in the genus Onchosaurus , but introduced a separate genus Onchopristis .

Ernst Stromer von Reichenbach (around 1914)

The generic name chosen by Stromer is derived from the two ancient Greek words όγκος ( ónkos = "barb") and πρίστης ( pristis = "saw").

Haug's first description was essentially based on some fragmentarily preserved rostral teeth from the Lower Cretaceous Djoua Valley in today's Algeria, while the finds from the Bahariya Formation in Egypt described by Stromer included not only completely preserved rostral teeth but also fragments of the partially ossified rostrum . In 1925 Stromer described a largely completely preserved rostrum about 1 m long with still attached fragments of the rostral teeth, skull fragments and parts of the spine. Haug also described ossified vertebrae of a cartilaginous fish from the Algerian find layers , which he ascribed to the taxon Platyspondylus foureaui . In 1927 Stromer added the teeth of a cartilaginous fish to his fossil record of the Bahariya Formation, which he described as Squatina aegyptiaca (= Sechmetia aegyptiaca Werner , 1989) and which for a long time were interpreted as the oral teeth of Onchopristis numidus . Later discoveries showed that the isolated vertebrae clearly belonged to Onchopristis numidus , but the oral teeth apparently did not.

As early as 1948, David Dunkle reported on a similar, fragmentary rostral tooth from the Woodbine formation in Texas , which he interpreted as belonging to the genus Onchopristis . After further discoveries, including complete rostral teeth, from the same formation in the 1950s, Charles L. McNulty and Bob H. Slaughter described a second species of the genus Onchopristis in 1962 , which they named Onchopristis dunklei in honor of Dunkle . Further finds followed and in 1971 John T. Thurmond described a further subspecies from the Walnut formation as Onchopristis dunklei precursor in addition to the nominate form Onchopristis dunklei dunklei .

A 1977 as Onchopristis dunklei precursor described finding from the Campanian - Maastrichtian of New Zealand was first as a possible confirmation of the related genus Sclerorhynchus ( Sclerorynchus? Sp. Counted and later as) Australopristis wiffeni placed in a separate genus.

Temporal and geographical distribution

In 2009, Barbara E, Wueringer and coauthors give the temporal distribution of the genus Onchopristis with Barremium to Cenomanium, which would correspond to an absolute age of about 130.7 to 93.9 Ma . The frequently occurring and easily identifiable rostral teeth of Onchopristis numidus are considered to be conductive for corresponding sediments in North Africa. Find reports from more recent deposits, however, are viewed as questionable.

In 2001 Jürgen Kriwet and Karina Kussius list a total of 25 sites for the genus from various formations in North Africa, North America, Europe and India. Find reports of Onchopristis , which can possibly be assigned to Onchopristis numidus , are also available from Brazil .

features

Rostral tooth of Onchopristis numidus

The present fossil material of Onchopristis comprises numerous isolated teeth, including both normal (oral) teeth and rostral (rostral) teeth. As a major exception, Stromer already described fragments of the rostrum and an almost complete rostrum with articulated rostral teeth. An articulated (anatomically related) partial skeleton from Morocco was added later, which shows the assignment of rostral and oral teeth to Onchopristis numidus .

The body shape can only be reconstructed hypothetically in analogy to better preserved representatives of the Sclerorhynchidae, but it should have essentially corresponded to that of the recent saw sharks and saw rays. The existing fragments of the rostrum allow the reconstruction of a rostrum in the species Onchopristis numidus , which can have reached two meters in length. In analogy to other species it is assumed that the rostrum made up about 20 to 30 percent of the body length. Other authors give for the construction plan of the Sclerorhynchidae in general a ratio of the rust ral length to the total body length of 1: 3.27. Stromer himself suspected a total body length of up to 8 m for Onchopristis numidus . With these more recent estimates, the almost complete rostrum of about 1 m in length described by Stromer would have a total body length of about 3.3 m and for the estimated, reconstructed length of the largest rostral fragments a maximum total body length of about 6.5 m.

Rostral fragment and rostral teeth from Onchopristis numidus

The diagnosis of the genus is based on the shape of the rostral teeth, which are up to seven centimeters long. These have an elongated, lanceolate crown made of dentine (orthodentine) with continuous tooth enamel , which are sharp-pointed and curved backwards. The front edge of the teeth is smooth, on the concave, non-keeled rear edge, they have the eponymous barbs on the outside, facing backwards. Two types are distinguished according to their shape. In Onchopristis numidus generally only one barb is formed, Onchopristis dunklei has three to five such hooks.

In contrast to the more recent saw rays , the rostral teeth in Onchopristis , similar to the recent saw sharks, are of different lengths and are distributed irregularly on the sides of the rostrum. They are not anchored in deep pits of the rostral cartilage, but rather, similar to the more recent saw sharks, are largely rooted in the connective tissue. Only the larger teeth correspond with shallow, scar-like pits on the sides of the rostral cartilage. The similarity of the rostral teeth with the recent saw sharks allows the conclusion that lost rostral teeth in onchopristis were constantly being replaced by new teeth.

Stromer describes the largely complete rostrum available to him as "medium-slim". The dorsoventrally flattened rostrum is initially only slightly narrower towards the front and only tapers more rapidly towards the tip. The front end is convex. The lateral edges of the rostrum are accompanied both dorsally and ventrally by a shallow groove, in which the nerve cords for the transmission of the signals from the Lorenzini ampoules presumably run .

Paleecology

Onchopristis dunklei fossil finds come exclusively from offshore, marine deposits. Remains of Onchopristis numidus , on the other hand, are also found in fluvial sediments , often far inland, away from the former coastlines. For the latter species, an at least partial adaptation to a life in freshwater is assumed.

In 2005 an upper jaw of Spinosaurus (MSNM V4047), found in 1975 in the Kem-Kem formation , was described, in which a single vertebral body was stuck in an alveolus , which probably originates from Onchopristis . Since then, Spinosaurus has often been depicted as hunting Onchopristis , especially in popular scientific depictions . However, the find is not considered to be reliable fossil evidence for a corresponding predator-prey relationship .

Individual evidence

  1. ↑ a b c d e E. Stromer: Results of Prof. E. Stromer's research trips in the deserts of Egypt: II. Vertebrate remains of the Baharîje stage (lowest Cenoman): 4. The saw of the Pristid Onchopristis numidus Haug sp. and about the saw sharks' saws. In: Abhandlungen der Bayerische Akademie der Wissenschaften, Mathematisch-Physische Klasse , Volume 28, 8th Abhandlung, 1917, pp. 1–28 ( digitized version ).
  2. ↑ a b c d E. Stromer: Results of Prof. E. Stromer's research trips in the deserts of Egypt: II. Vertebrate remains of the Baharîje stage (lowest cenomaniac): 8. A skeletal remains of the pristid Onchopristis numidus Haug sp. In: Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-Physische Klasse , Volume 30, 6th Abhandlung, 1917, pp. 11-22 ( digitized version ).
  3. ↑ E. Stromer: Results of Prof. E. Stromer's research trips in the deserts of Egypt: II. Vertebrate remains of the Baharîje stage (lowest cenomaniac): 9. The plagiostomes, with an appendix about the Cenozoic and Mesozoic dorsal fin spines of Elasmobranchi. In: Treatises of the Bavarian Academy of Sciences, Mathematical and Natural Science Department , Volume 31, 5th Treatise, 1927, pp. 1-64 ( digitized version ).
  4. ^ A b DB Dutheil & PM Brito: Articulated cranium of Onchopristis numidus (Sclerorhynchidae, Elasmobranchii) from the Kem Kem beds, Morocco. In: First North African Vertebrate Palaeontology Meeting, Marrakech, Morocco, May 25-27, 2009 , 2009, 1 p. (Abstract).
  5. ^ CL McNulty & BH Slaughter: A New Sawfisch from the Woodbine Formation (Cretaceous) of Texas. In: Copeia , Volume 1962, Number 4, 1962, pp. 775-777, ( JSTOR 1440678 ).
  6. ^ JT Thurmond: Cartilaginous fishes of the Trinity Group and related rocks (Lower Cretaceous) of north central Texas. In: Southeastern Geology , Volume 13, 1971, pp. 207-227.
  7. ^ A b IW Keyes: Records of the northern hemisphere Cretaceous Sawfish genus Onchopristis (order batoidea) from New Zealand. In: New Zealand Journal of Geology and Geophysics , Volume 20, Number 2, 1977, pp. 263-272 ( digitized ).
  8. ↑ a b J. Kriwet & K. Kussius: Paleobiology and Paleobiogeography of sclerorhynchid sawfishes (Chondrichthyes, Batomorphii). In: Revista Espanola de Paleontologia , number Extraordinario, 2001, pp. 35-46 ( digitized version ).
  9. ↑ DM Martill & N. Ibrahim: Aberrant rostral teeth of the sawfish Onchopristis numidus from the Kem Kem beds (? Early Late Cretaceous) of Morocco and a reappraisal of Onchopristis in New Zealand. In: Journal of African Earth Sciences , Volume 64, 2012, pp. 71-76, ( abstract ).
  10. ↑ a b c BE Wueringer, L. Squire Jr. & SP Collin: The biology of extinct and extant sawfish (Batoidea: Sclerorhynchidae and Pristidae). In: Reviews in Fish Biology and Fisheries , Volume 19, 2009, pp. 445-464 ( doi: 10.1007 / s11160-009-9112-7 ).
  11. ↑ MA O'Leary, ML Bouaré, KM Claeson, K. Heilbronn, RV Hill, J. McCartney, JA Sessa, F. Sissoko, L. Tapanila, E. Wheeler & EM Roberts: Stratigraphy and Paleobiology of the Upper Cretaceous - Lower Paleogenic Sediments from the Trans-Saharan Seaway in Mali. In: Bulletin of the American Museum of Natural History , number 436, 2019, 177 pp. ( Available ).
  12. ^ MA Medeiros, RM Lindoso, ID Mendes & I. de Souza Carvalho: The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America. In: Journal of South American Earth Sciences , Volume 53, 2014, pp. 50-58, ( digitized ).
  13. ↑ a b PC Sternes & K. Shimada: Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data. In: Historical Biology , Volume 31, 2018, pp. 1323-1340, ( digitized ).
  14. ↑ a b Ch. J. Underwood, MM Smith & Z. Johanson: Sclerorhynchus atavus and the convergent evolution of rostrum-bearing chondrichthyans. In: Geological Society Special Publications . Number 430, 2015, pp. 129-136 doi : 10.1144 / SP430.7 .
  15. ↑ J. Amalfitano, L. Giusberti, FM Dalla Vecchia & J. Kriwet: First skeletal remains of the giant sawfish Onchosaurus (Neoselachii, Sclerorhynchiformes) from the Upper Cretaceous of northeastern Italy. In: Cretaceous Research , Volume, 2017, pp. 124–135, ( digitized ).
  16. ↑ H. Capetta: Handbook of Paleoichthology. Chondrichthyes II: Mesozoic and Cenozoic Elasmobranchii. Volume 3, Part 2, Verlag Dr Friedrich Pfeil, reprint 1987, (Orig .: Gustav Fischer Verlag) ISBN 978-3-89937-046-1 , p. 152ff.
  17. ^ BH Slaughter & S. Springer: Replacement of Rostral Teeth in Sawfishes and Sawsharks. In: Copeia , Volume 1968, Number 3, 1968, pp. 499-506, ( digitized version ).
  18. ↑ N. Ibrahim, PC Sereno, DJ Varricchio, DM Martill, DB Dutheil, DM Unwin, L. Baidder, HCE Larsson, S.amir Zouhri & A. Kaoukaya: Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco. In: ZooKeys - Monograph , Volume 928, 2020, pp. 1-216, doi : 10.3897 / zookeys.928.47517 .
  19. ↑ C. dal Sasso, S. Maganuco, E. Buffetaut & MA Mendez: New Information on the Skull of the Enigmatic Theropod Spinosaurus, with Remarks on its Size and Affinities. In: Journal of Vertebrate Paleontology , Volume 25, Number 4, 2005, pp. 888-896, ( digitized ).
  20. ^ MAF Sales & CL Schultz: Spinosaur taxonomy and evolution of craniodental features: Evidence from Brazil. In: PLoS One , Volume 12, Number 11, 2017, Article e0187070, doi : 10.1371 / journal.pone.0187070 .

Web links

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