Australosomus, Psarolepis, Qingmenodus, Onychodus, Selenodus and Strunius

Australosomus merlei (Priem 1924, Pivetau 1930; Early Triassic; 230 mya, 12cm long) is a traditional member of the Pholidopleuriformes and Chondrostei, but nests here as a paleoniscid basal to Strunius. Other workers document an upper temporal fenestra but that represents the hole of a dislocated intertemporal.

Psarolepis romeri (Yu 1998; Zhu et al. 2014; Long 2001; Late Silurian; mandible 3.3cm) is known from parts of its face and a complete mandible perhaps lacking a medial spiral tooth whorl at its tip. Other elements include a dorsal spike, plus cheek and mandible elements with tooth rows. Here Psarolepis nests with Strunius. The upturned and short rostrum includes large incurrent and excurrent nares. Nearly all the pebbled bones of the cranium are fused together, except for a straight suture between the prefrontals and parietals. An internal premaxilla separates toothed lacrimals, as in sharks, with teeth directed medially.. The toothy mandible is well preserved. Spikes lead the pectoral fins.

Strunius rolandi (Jessen 1966; originally Glyptomus rolandi Gross 1956; up to 10 cm in length; Late Devonian) was considered a lobe-fin fish with ray fins. Here it nests within the Palaeoniscidae, derived from Australosomus and Pteronisculus. The tail is straight, like Latimeria. The maxilla extends to the quadrate. The orbit is within an orbit's width of the snout tip. An upper temporal fenestra isbarely present. Onychodus (below) is a relative sharing a tooth whorl between the two dentary tips.

Qingmenodus yui (Lu and Zhu 2010, Lu et al 2016, Early Devonian) was considered an early lobe fin. Early onychodontids are palaeoniscids. The dorsal skull bones are reidentified here. Illustration shown about 1.5x life size.

Onychodus sigmoides (Newberry 1857; Onychodus jandemarra Andrews et al. 2006; Late Devonian; 10cm skull, 47 cm length with larger specimens up to 2m in length) is a sister to the much smaller Strunius. Both are considered members of the Onychodontidae, not nesting within the Palaeonisciformes. The large, rotating tooth whorl at the dentary and long premaxilla extending below the orbit are key traits.

Selenodus aquesbiae (Schultze 1973, Mondéjar-Fernández 2019; Middle Devonian) has a deep lacrimal fused to a maxilla and deep rostrum. Here it nests with Strunius and Onychodus.

Andrews M, Long J, Ahlberg P, Barwick R and Campbell K 2006. The structure of the sarcopterygian Onychodus jandemarrai n. sp. from Gogo, Western Australia: with a functional interpretation of the skeleton. Transactions of the Royal Society of Edinburgh. 96 (3): 197–307.

Mondéjar-Fernández J 2019. A new onychodont (Osteichthyes; Sarcopterygii) from the Middle Devonian of Morocco and its bearing on early osteichthyan evolution. Journal of Systematic Palaeontology 0: 1–34. http://dx.doi.org/10.1080/14772019.2019.1655495

Gross W 1933 1936 Die Fische des baltischen Devons, Palcteontographica A 79:1-74.

Jessen 1966. in Piveteau (Ed.). Traite de paleontologie. Tome 4. L'origine des Vertebres, leur expansion dans les eaux douces et le milieu marin. Vol. 3. Actinopterygiens, Crossopterygiens, Dipneustes. Masson & Cie, Paris.

Long JA 2001. On the relationships of Psarolepis and the onychodontiform fishes. Journal of Vertebrate Paleontology. 21 (4): 815–820.

Lu J and Zhu M 2009. An onychodont fish (Osteichthyes, Sarcopterygii) from the Early Devonian of China, and the evolution of the Onychodontiformes. Proceedings of the Royal Society B doi:10.1098/rspb.2009.0708 Published online.

Lu J et al 2016. A Devonian predatory fish provides insights into the early evolution of modern sarcopterygians. Science Advances 2(6):e1600154, doi:10.1126/sciadv.1600154

Newberry JS 1857. Fossil fishes from the Devonian rocks of Ohio. Geological
Survey of Ohio: Bulletin National Institute: 1–120.

Piveteau J 1930. C. R. Acad. Sci. Paris, 191: 456 pp.

Priem F 1924. Paleontologie de Madagascar. XII. Les Poissons fossiles. Ann. Paleont., vol. 13: 105–132.

Schultze H-P 1973. Crossopterygier mit heterozerker Schwanzflosse aus dem Oberdevon Kanadas, nebst einer Beschreibung von Onychodontida-Resten aus dem Mitteldevon Spaniens und aus dem Karbon der USA. Palaeontographica, Abteilung A, 143:188–208.

Yu X 1998. A new porolepiform-like fish, Psarolepis romeri, gen. et sp. nov. (Sarcopterygii, Osteichthyes) from the Lower Devonian of Yunnan, China. Journal of Vertebrate Paleontology. 18 (2): 261–274.

Zhu M and Yu X 2002. A primitive fish close to the common ancestor of tetrapods and lungfish. Nature 418: 767–770.

wiki/Australosomus
wiki/Strunius
wiki/Onychodus
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wiki/Onychodontiformes
wiki/Qingmenodus
wiki/Psarolepis