Schizorhiza

Schizorhiza is an extinct genus of schizorhizid sclerorhynchoid that lived during the Late Cretaceous. It contains one valid species, S. stromeri. It lived from the Santonian to Maastrichtian and its fossils have been found in Africa, the Middle East, North America, and South America.[3]

Schizorhiza
Temporal range:
Schizorhiza stromeri rostrum
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Chondrichthyes
Superorder:
Batoidea
Order:
Rajiformes
Suborder:
†Sclerorhynchoidei
Family:
†Schizorhizidae
Genus:
†Schizorhiza

Weiler, 1930[1]
Binomial name
†Schizorhiza stromeri
Weiler, 1930
Synonyms
  • Schizorhiza weileri Serra, 1933[2]

Taxonomy

Schizorhiza stromeri was named by Wilhelm Weiler in 1930 for rostral denticles from the Nubian Sandstone of Egypt. The species was named in honor of Ernst Stromer.[1] A second species, S. weileri, was named by Giselda Serra in 1933 for rostral denticles from Libya.[2] It is considered a junior synonym of S. stromeri.[4]

Description

Schizorhiza is characterized by its robust rostrum with over 1,800 denticles arranged in dense batteries, which form a continuous cutting edge along each side.[4] Each denticle was replaced by a series of smaller denticles nested inside its roots and new rows of denticles grew from the end of the rostrum.[5] Among sclerorhynchoids, this denticle arrangement and replacement system is only found in Schizorhiza and its close relative Harranahynchus.[6] The rostrum was likely used for swiping and slicing prey like sawfishes[4] and has earned Schizorhiza the common name of "slasher ray".[7]

References
  1. Weiler, W. (1930). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. VI. Beschreibung von Wirbeltier-Resten aus dem nubischen Sandsteine Oberägyptens und aus ägyptischen Phosphaten nebst Bemerkungen über die Geologie der Umgegend von Mahamîd in Oberägypten. Fischreste aus dem nubischen Sandstein von Mahamîd und Edfu und aus den Phosphaten Oberägyptens und der Oase Baharîje". Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung. 7: 12–36.
  2. Serra, G. (1933). "Di una nuova specie di Schizorhiza del Maestrichtiano della Tripolitania". Rivista Italiana di Paleontologia. 39: 103–108.
  3. Cappetta, H. (2012). Handbook of Paleoichthyology. Volume 3E. Chondrichthyes. Mesozoic and Cenozoic Elasmobranchii: Teeth. Munich: Verlag Dr. Friedrich Pfeil. ISBN 978-3-89937-148-2.
  4. Kirkland, J.I.; Aguillón-Martínez, M.C. (2002). "Schizorhiza: a unique sawfish paradigm from the Difunta Group, Coahuila, Mexico". Revista Mexicana de Ciencias Geológicas. 19 (1): 16–24.
  5. Smith, M.M.; Riley, A.; Fraser, G.J.; Underwood, C.; Welten, M.; Kriwet, J.; Pfaff, C.; Johanson, Z. (2015). "Early development of rostrum saw-teeth in a fossil ray tests classical theories of the evolution of vertebrate dentitions". Proceedings of the Royal Society B: Biological Sciences. 282 (1816): 20151628. doi:10.1098/rspb.2015.1628.
  6. Kaddumi, H.F. (2009). "A new genus and species of sawfishes (Chondrichthyes: Batoidea) from the late Maastrichtian sediments of Harrana". Fossils of the Harrana Fauna and the Adjacent Areas. Eternal River Museum of Natural History. pp. 178–187.
  7. Gibson, S.Z. (2015-10-30). "The "slasher" ray: An extinct fish with a saw-like nose". PLOS Paleo. Retrieved 2023-03-20.
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