Typhloesus

Typhloesus; Temporal range: Serpukhovian PreꞒ Ꞓ O S D C P T J K Pg N
	Fossil specimens
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Superphylum:	Lophotrochozoa
Phylum:	Mollusca (?)
Genus:	†Typhloesus; (Conway Morris, 1990)
Species:	†T. wellsi
Binomial name
	†Typhloesus wellsi; (Melton and Scott, 1973)

Typhloesus wellsi is an extinct species of enigmatic bilaterian animals from the Bear Gulch Limestone. It was once thought to be the first body fossil of a conodont, based on what turned out to be its gut contents; it is now thought to exhibit a radula, which would make it a mollusc,^[1] although different types of animal have independently evolved radula-like features. Mark Purnell, of the Centre for Palaeobiology at the University of Leicester, said that it was not definitively known "what this weird thing is".^[2]

Discovery

Typhloesus was first described back in 1973 from Carboniferous rocks in Montana.^[3] The animal was then jokingly referred to as the ‘alien goldfish’ by subsequent studies.^[1] Because of its highly enigmatic nature, this organism was only mentioned briefly in several papers.^[1] It was then thought to have been the first known body fossil of a conodont, which are a primitive group of jawless agnathan fish distantly related to lampreys and hagfish.^[4] This was based on the presence of "conodont elements", which are the small comb-like teeth of those animals. The teeth however were actually located in the gut contents of the Typhloesus, meaning that while it wasn't a conodont, they were a part of its diet.^[1] The animals taxonomy would be shrouded in mystery for over 30 years until in September 2022, when a new paper published revealed several potential mollusk-like features of the animal.^[1]

Description

It has a fusiform (spindle-shaped) body, with a maximum length of 90 mm. At the posterior or backside of the animal is a

caudal fin, which was supported by two sets of orthogonal fin rays. The exterior lacks any other organs. The internal anatomy consists of a foregut and a midgut. The gut lacks a midsection and an anus. Beneath the midgut is a disc shaped organ, tentatively called a ferrodiscus; the purpose of this organ is unknown, however it has a high concentration of iron.^[3]