Protospinax, Rhinobatos, Lessiniabatis, Harpacanthus, Menaspis, Raja, Leucoraja and Pristis

Protospinax annectans (Woodward 1919, Jambura et al 2023, Lower Tithonian, Late Jurassic, 90cm long) is traditionally nested between angel sharks and saw sharks, as it does here.

Rhinobatos rhinobatos (Linneaus 1758; up to 1.47m) is the extant common guitarfish, a transitional taxon between sharks and skates + rays. The mouth and gills are below the pectoral fins that extend forward anterior to the eyes, which rise to the top of the skull.

Rhina anclystoma (Bloch and Schneider 1801) is a transitional taxon between sharks and guitarfish.

Pristis pristis (Linck 1790; up to 7.6m) is the extant sawfish, a sister to the guitarfish (Rhinobatos) in the LRT. The nasal dermal denticles are larger than the teeth. They become worn with age and are not replaced. As in sister taxa the rostrum is a huge sensory organ for finding buried prey. The saw is also used to swipe and incapitate swimming fish and pin fish against the sea floor. Prey are swallowed whole.

The prefrontals (brown) contribute to the width of the skull. Gills and nares are ventral.

Leucoraja erinacea (Malm 1877; originally Raja erinacea Mitchell 1825; Johanson et al. 2019) is the extant little skate. Note the greater pectoral fin relative to the shorter rostrum compared to related taxa.

Raja clavata (Linneaus 1758; 1m) is the extant thornback ray. The back is covered in a row of thorny spines, reappearances form placoderm ancestors. Note the broad transverse jaws and pavement teeth along with the elongate nasals.

Lessiniabatis aenigmatica (Marramá et all 2019, Eocene, 70cm) is a dasyatoid stingray unique in having a thoracolumbar synarcual extending backward beyond the pelvic girdle, a tail that is extremely short and not protruding from the posterior edge of the pectoral disc, and pectoral radials that are proximally fused with one another.

Menaspis armata (Ewald 1848, Late Permian, >15cm long) restored as a thornback ray (Raja clavata) exposed in ventral view.

Harpacanthus fimbriatus (Traquair 1886; Lund and Grogan 2004; Carboniferous; Bear Gulch Formation 320mya) nests nests with the skates in the LRT. Here the six 'claspers' are instead homologous to similar structues in Menaspis. The fossil exposes the dorsal view.

Bendix-Almgreen SE 1971. The anatomy of Menaspis armada and the phylogenetic affinities of the menaspid bradyodonts. Lethaia 4(1):21–49.

Bloch MC and Schneider JG 1891. Systema anclystoma.

Ewald J 1848. Über Menaspis, eine neue fossile Fischgattung. Berichte Über die zur Bekanntmachung Geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zur Berlin 1848:33-35.

Jäckel O 1890. Über Menaspis, nebst allgemeinen Bemerkungen über die systematische Stellung der Elasmobranchii. Sitzungsb. Ges. nature. Freunde, Berlin 1891: 115–131.

Jambura PL et al (12 co-authors) 2023. Systematics and Phylogenetic Interrelationships of the Enigmatic Late Jurassic Shark Protospinax annectans Woodward, 1918 with Comments on the Shark–Ray Sister Group Relationship. Diversity:15(311) 1-43.. https:// doi.org/10.3390/d15030311

Johanson Z, Mertin K, Fraser G and James K 2019. The Synarcual of the Little Skate, Leucoraja erinacea: Novel Development Among the Vertebrates. Front. Ecol. Evol., 05 February 2019 | https://doi.org/10.3389/fevo.2019.00012

Linck HF 1790. Versuch einer Eintheilung der Fische nach den Zähnen. - Magazin für das Neueste aus der Physik und Naturgeschichte 6 (3): 28-38. Gotha.

Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

Lund R and Grogan E 2004. Five new euchondrocephalan Chondrichthyes from the Bear Gulch Limestone (Serpukhovian, Namurian E2b) of Montana, USA. In G. Arratia, M. Wilson, R. Cloutier (eds.), Recent Advances in the Origin and Early Radiation of Vertebrates 505-531.

Malm AW 1877. Göteborg och Bohusläns fauna, Ryggradsdjvren

Marramá G et al (4 co-authors) 2019. A bizarre Eocene dasyatoid batomorph (Elasmobranchii, Myliobatiformes) from the Bolca Lagerstätte (Italy) reveals a new, extinct body plan for stingrays. Nature scientific reports 9 article number 14087. https://doi.org/10.1038/s41598-019-50544-y

Mitchell SL 1825. The hedgehog-ray - a species of Fish taken occasionally near New-York, in the Atlantic Ocean, and now, as is believed, for the first time described American Journal of Science and Arts, 9: 290.

Ortlam D 1986. Neue Aspekte zur Deutung von Menaspis armata Ewald (Kupferschiefer, Zechstein 1, Deutschland) mit Hilfe der stereoskopischen Röntgentechnik. Geologisches Jahrbuch Reihe A, Band A 81.

Patterson C 1968, Menaspis and the bradyodonts. In: T. Ørvig, Current Problems of Lower Vertebrate Phylogeny. (Hrsg.): Nobel Symposium. Band 4. Almquist and Wiksell, Stockholm 1968, S. 171–205.

Schaumberg G 1992. Neue Informationen zu Menaspis armata Ewald. Paläontologische Zeitschrift 66:311.

Traquair RH 1886. XLV.—On Harpacanthus, a new genus of Carboniferous Selachian Spines , Annals and Magazine of Natural History: Series 5, 18:108, 493-496.

Woodward AS 1919. On Two New Elasmobranch Fishes (Crossorhinus jurassicus, sp. nov., and Protospinax annectans, gen. et sp. nov.) from the Upper Jurassic Lithographic Stone of Bavaria. Proc. Zool. Soc. Lond. 1919, 13, 231–235.

wiki/Protospinax
wiki/Menaspis
wiki/Common_guitarfish
wiki/Pristis
wiki/Sawfish
wiki/Little_skate - Leucoraja
wiki/Thornback_ray_Raja
wiki/Harpacanthus
wiki/Lessianiabatis - not yet posted