Promissum, Panderodus, Lasanius, Euphanerops, Birkenia, Thelodus and Drepanolepis

Fish - Chordata

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Basal Archosauromorpha

Lasanius problematicus (Traquair 1899; Middle Silurian; 5cm) is a birkeniid with longer pectoral fins and a distinct set of dorsal spines.

Lasanius, Birkenia and Coilia – the origin of fins in the tetrapod lineage3

Birkenia elegans (Traquair 1899; Middle Silurian; up to 10cm) is a jawless, finless chordate with scales, twin nostrils and a hypocercal tail. Bony hooks top the dorsal region. Cilia line the permanently open jaws. Gill bars and gill openings are present.

Promissum pulchrum (Kovacs-Endrody 1986, Gabbott, Aldridge and Theron 1995; Goudemand, Orchard, Urdy, Bucher and Tafforeau 2011). Late Ordovician, est 40cm in length) is a large conodont.

According to Gabbot, et al 1995 "Conodonts are extinct Cambrian/Triassic vertebrates, soft bodied apart form the phosphatic elements of their feeding apparatuses." Their cladogram nested conodonts between hagfish + lampreys and anaspids + ostracoderms. Kovacs-Endrody called this 'the earliest known vascular plant.'

Panderodus unicostatus (Branson and Mehl, 1933, Smith et al 1987, Murdock and Smith 2021) was an Early Silurian conodont known from the anterior half. The lancelet-like atrium is labeled in blue here. The eyes and preoral lobe were traced using DGS methods.

Euphanerops longaevus (Woodard 1900; Janvier and Arsenault 2007; Late Devonian) was originally compared to lampreys, but here nests basal to sturgeons with an Ordovician genesis. Tiny pelvic fins appear for the first time. The posteriordorsal fin creates a hypocercal caudal fin.

Drepanolepis maerssae (Wilson and Caldwell 1993, 1998; Early Devonian; 2cm in length) is a traditional thelodont and a member of the Furcacaudiformes (forked tails). Drepanolepis is derived from Birkenia (above), but with a taller, shorter, angelfish-like body. They both have a ventral mouth and a hypocercal tail, somewhat elaborated in Drepanolepis. The gill atrium remains quite large and the nasal extends from the orbit down to the oral cavity, which remains like that of a lancelet, without jaws.

Sphenonectris turnerae (Wilson and Caldwell 1993, 1998; Early Devonian) has a displaced oral cavity and was originally published upside-down.

Furcacauda fredholmae (Wilson and Caldwell 1993, 1998; Early Devonian; 9cm in length)

Pezzopallichthys ritchiei (Wilson and Caldwell 1993, 1998; Late Silurian; 5cm in length) had a toadfish-like morphology. The ventral oral cavity is bright green here.

Thelodus parvidens (Agassiz 1839; GLAHM–V8304, Early Silurian; 5–15cm in length) this specimen was published in a popular book, Long 1995. Soft tissue is preserved. This specimen nests basal to sturgeons. Click to enlarge image.

Agassiz L 1839. Fishes of the Old Red Sandstone. In Merchison's Silurian System. Künstliche Steikerne von Konchylien und Fische. Neues Jahrbuch Mineralogie.

Branson EB and Mehl MG 1933. Conodonts from the Bainbridge (Silurian) of Missouri. University of Missouri Studies, 8, 39–52.

Briggs DEG, Clarkson ENK and Aldridge RJ 1983. The conodont animal. Lethaia. 16 (1): 1–14.

Donoghue and Forey PL and Aldridge RJ May 2000. Conodont affinity and chordate phylogeny. Biological Reviews. 75 (2): 191–251.

Gabbot SE, Aldridge RJ and Theron JN 1995. A giant conondont with preserved muscle tissue from the Upper Ordovician of South Africa. Nature 374:800–803.

Goudemand N, Orchard MJ, Urdy S, Bucher H and Tafforeau P 2011. Synchrotron-aided reconstruction of the conodont feeding apparatus and implications for the mouth
of the first vertebrates. PNAS 108(21):8720–8724.

Janvier P and Arsenault M 2007. The anatomy of Euphanerops longaevus Woodward, 1900, an anaspid-like jawless vertebrate from the Upper Devonian of Miguasha, Quebec, Canada. Geodiversitas 29 (1) : 143-216.

Kovacs-Endrody E 1986. The earliest known vascular plant, or a possible ancestor of vascular plants in the flora of the Lower Silurian Cedarberg Formation, Table Mountain Group, South Africa. Ann. Geol. Surv. S. Afr. 20, 93-118.

Long JA 1995. The Rise of Fishes. Johns Hopkins University Press. Baltimore and London.

Liu HT and Zhou JJ 1965. A new sturgeon from the Upper Jurassic of Liaoning, North China. Vertebrata PalAsiatica 9, 3, 237-247. In Chinese with English abstract. PDF

Murdock DJE and Smith MP 2021. Panderodus from the Waukesha Lagerstätte of Wisconsin, USA: a primitive macrophagous vertebrate predator. Papers in Palaeontology. 7 (4): 1977–1993. doi:10.1002/spp2.1389

Smith MP, Briggs DEG and Aldridge RJ 1987. A conodont animal from the Lower Silurian of Wisconsin, U.S.A., and the apparatus architecture of panderodontid conodonts. 91–104. In ALDRIDGE, R. J. (ed.) Palaeobiology of conodonts. Ellis Horwood, 180 pp.

Traquair RH 1898. Report on fossils fishes. Summary of Progress of the Geological Survey of the United Kingdom for 1897: 72-76.

Traquair RH MD LLD FRS 1898. IX Notes on Palœozoic fishes. Annals and Magazine of Natural History, 2(7): 67–70.

Traquair R 1899. XXXII Report on Fossil Fishes collected by the Geological Survey of Scotland in the Silurian Rocks of the South of Scotland. Transactions of the Royal Society of Edinburgh, 39(3): 827–864.

Wilson MVH and Caldwell MW 1993. New Silurian and Devonian fork-tailed 'thelodonts' are jawless vertebrates with stomachs and deep bodies. Nature. 361 (6411): 442–444.

Wilson MVH and Caldwell MW 1998. The Furcacaudiformes, a new order of jawless vertebrates with thelodont scales, based on articulated Silurian and Devonian fossils from northern Canada. Journal of Vertebrate Paleontology 18 (1): 10-29.

Woodward AS 1900. On a new ostracoderm fish (Euphanerops longaevus) from the Upper Devonian of Scaumenac Bay, Quebec, Canada. Magazine of Natural History ser. 7, 5: 416-419.

wiki/Birkenia
wiki/Lasanius
wiki/Birkeniiformes
wiki/Drepanolepis
wiki/Furcacaudiformes
wiki/Euphaneropidae
wiki/Thelodus
wiki/Promissum
wiki/Panderodus

Conodontomorpha

Birkenia

Leptolepis

Coilia

Elopomorpha

Elops

Cypriniformes

Danio

Engraulidae

Engraulis

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