Boreosomus, ?Pachycormus macropterus BRLSI M1332, Bonnerichthys, Protosphyraena, Germanostomus, Orthocormus, Aspidorhynchus, Pachycormus, Saurichthys and Yelangichthys

Boreosomus arcticus (aka Diaphorognathus, Woodward 1912; Priem 1924; Early Triassic; 250 mya, 10-20cm) nests with two pachycormids including Ohmdenia. Note the procumbent dentary teeth and anterior dorsal fin.

?Pachycormus macropterus (Cawley et al. 2018; Early Jurassic, BRLSI M1332) reported on 3D specimens attributed to Pachycormus, but here nests closer to Ohmdenia (above).

Bonnerichthys gladius (Friedman et al. 2010; originally Portheus gladius, then Protosphyraena gladius (Cope 1873) est. 4-5m long; Late Cretaceous) was considered a giant, toothless, Niobrara plankton eater related to Pachycormus. Shown here is the original reconstruction (ghosted) and a DGS reconstruction (color) based on bones in Friedman et al.).

Pachycormus macropterus (Agassiz 1833; Wretman, Blom and Kear 2016; Early Jurassic, 1m long) is the namesake for the clade Pachycormiformes. Here that clade nests with Osteoglossum (above) at the base of the Teleostei under the last common ancestor method. The pelvic fins are either vestiges. Spike-like fins appear between the pectorals, as in Protosphyraena and other related taxa.

This tuna-like specimen is considered basal to larger later suspension feeders, like Leedsichthys.

Cawley et al. 2018 reported on 3D specimens (e.g. BRLSI M1332) attributed to Pachycormus. Instead that specimen nests with Boreosomus and Ohmdenia.

Orthocormus, Aspidorhynchus and Protosphyraena in situ

Orthocormus roeperi (Weitzel 1930; Arratia and Schultze 2013; Early Jurassic; 45cm; BSPG 1993 XVIII-VFKO B1) is a basal pachycormiform with a short rostrum, most closely related to Aspidorhynchus.

Germanostomus pectopteri (Cooper et al 2022, SMNS 15815, Early Jurassic, 1m) was originally considered close to Ohmdenia, but here nests at the base of the long rostrum pachycormiformes, close to Protosphyraena (below) in the LRT. Scale bar = 10cm. The long gills cover an extended and probably flexible 'neck'.

Protosphyraena nitida (Leidy 1857; Late Cretaceous; 3m) was originally considered a basal barracuda and traditionally considered a member of the Pachycormiformes. Here it nests with Pachycormus and another Niobrara osteoglossiform, Ohmdenia, but closer to the Late Jurassic Solnhofen, Aspidorhynchus. This poorly ossified fast swimmer with long spiny pectoral fins had a sharp snout and large anterior fangs. Like a barracuda the small dorsal fin and small anal fin are mirror images of each other. Tail spine bones extend between the tail fin bones. Distinct from sister taxa, long, streaming pelvic fins originate close to the pectoral fins.

Aspidorhynchus acutirostris (Blainville 1818, Agassiz 1843, Frey and Tischlinger 2012; Late Jurassic, 60cm; WDC CSG 255) is not related to the bowfin (Amia), but to Protosphyraena and Osteoglossum. Some specimens are entangled with pterosaurs of similar size. The jugal forms the entire cheek. The postorbital is reduced to a slender arc. Several large teeth appear on the premaxilla.

Saurichthys ornatus (Agassiz 1843; up to 1m in length; Early Triassic to Mid Jurassic) is a long and derived pachycormid. More than 50 fossil species are known. The one in the diagram and the one in the photo are distinct species. The Gregory 1933 diagram is corrected with tetrapod homology colors.

Yelangichthys macrocephalus (Wu, Chang, Sun and Xu 2013, GMPKU-P1359, Middle Triassic) is a saurichthyan ray-fin fish with a crushing dentition, a short rostrum and a wide skull.

Agassiz L 1833, 1837 in Agassiz L. 1833-1843. Recherches sur les Poissons fossiles-I, I, III, Neuchatel, pp 1420.

Arratia G and Schultze H-P 2013. Outstanding features of a new Late Jurassic pachycormiform fi sh from the Kimmeridgian of Brunn, Germany and comments on current understanding of pachycormiforms. Pp. 87–120 in Mesozoic Fishes 5 – Global Diversity and Evolution, Arratia G, Schultze H-P and Wilson MVH (eds.).

Agassiz L 1843. Recherches sur les poissons fossiles: 5 vols, with atlas (Neuchâtel).

Blainville HMD de 1818. Poissons fossiles. Nouveau Dictionnaire d’Histoire Naturelle 27: 310–395.

Blom H and Kear BP 2016. Resolution of the Early Jurassic actinopterygian fish Pachycormus and a dispersal hypothesis for Pachycormiformes. Journal of Vertebrate Paleontology 36(5):e1206022. Online

Cooper SLA, Giles S, Young H and Maxwell EE 2022. Large †Pachycormiform
(Teleosteomorpha:†Pachycormiformes) from the Lower Jurassic of Germany, with Affinities
to the Suspension-Feeding Clade, and Comments on the Gastrointestinal
Anatomy of Pachycormid Fishes. Diversity 2022, 14, 1026. https://
doi.org/10.3390/d14121026

Frey E and Tischlinger H 2012. The Late Jurassic pterosaur Rhamphorhynchus, a frequent victim of the ganoid fish Aspidorhynchus?. PLoS ONE. 7 (3): e31945. Bibcode:2012PLoSO...7E1945F. doi:10.1371/journal.pone.0031945.

Friedman M et al 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science, 327 (5968). pp. 990-993. ISSN 0036-8075
http://eprints.gla.ac.uk/55074/

Friedman M 2011, 2012. Parallel evolutionary trajectories underlie the origin of giant suspension-feeding whales and bony fishes. Proceedings of the Royal Society B 279, 944–951. doi:10.1098/rspb.2011.1381

Leidy J 1857. Remarks on Saurocephalus and its allies. Transactions of the American Philosophical Society. 11: 91–95.

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

Weitzel K 1930. Drei Riesenfische aus den Solnhofener Schiefern von Langenaltheim. – Abh. Senckenberg. Naturforsch. Ges. 42 (2): 85-113.

Woodward AS 1912. Notes on some fish-remains from the Lower Trias of Spitzbergen. Bulletin of the Geological Institution of the University of Upsala 11:291-297.

Wretman L, Blom H and Kear BP 2016. Resolution of the Early Jurassic actinopterygian fish Pachycormus and a dispersal hypothesis for Pachycormiformes. Journal of Vertebrate Paleontology 36(5):e1206022. Online

Wu F, Chang M-m, Sun Yand Xu G 2013. A New Saurichthyiform (Actinopterygii) with a Crushing Feeding Mechanism from the Middle Triassic of Guizhou (China). PLoS ONE 8(12): e81010. doi:10.1371/journal.pone.0081010

Wu F-X, Sun Y-L and Fang G-Y 2018. A new species of Saurichthys from the Middle Triassic (Anisian) of Southwestern China. Vertebrata PalAsiatica 56(4):287–294. pdf

wiki/Bonnerichthys
wiki/Protosphyraena
wiki/Aspidorhynchus
wiki/Pachycormus
wiki/Orthocormus
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wiki/Saurichthys
wiki/Yelangichthys
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