Promissum, Lasanius, Euphanerops, Birkenia, Thelodus and Drepanolepis

Fish - Chordata

Basal Chordata

Chondrichthyes

Acipenseriformes

Placodermi

Siluriformes - Acanthodii

Conodontomorpha

Tetrapoda

Reptilia/Amniota

Lepidosauromorpha

Cephalerpeton clade

Captorhinidae

Milleretta Limnoscelis clade

Bolosaurus Diadectes clade

Turtle Pareiasaur clade

Fenestrasauria • Pterosauria

Protosquamata

Squamata

Archosauromorpha

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.'

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.

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

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

Traquair RH M.D. 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

Conodontomorpha

Birkenia

Leptolepis

Coilia

Elopomorpha

Elops

Cypriniformes

Danio

Engraulidae

Engraulis

© After5

contact: info@reptileevolution.com

Home Page