Tylopterella

Tylopterella Temporal range: Ludlow, 422.9–418.7 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Top view of the holotype specimen of T. boylei recovered at Elora, in Canada. Carapace ornamentation enlarged.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Order:	†Eurypterida
Superfamily:	†Onychopterelloidea
Family:	†Onychopterellidae
Genus:	†Tylopterella Størmer, 1951
Type species
†Tylopterella boylei Whiteaves, 1884

Tylopterella is a genus of eurypterid, a group of extinct aquatic arthropods. Only one fossil of the single and type species, T. boylei, has been discovered in deposits of the Late Silurian period (Ludlow epoch) in Elora, Canada. The name of the genus is composed by the Ancient Greek words τύλη (túlē), meaning "knot", and πτερόν (pteron), meaning "wing". The species name boylei honors David Boyle, who discovered the specimen of Tylopterella.

It is a poorly-known genus whose carapace (dorsal plate of the prosoma, head) was semiovate bordered by a marginal rim, with eyes laterally placed, a preabdomen and postabdomen (the two halves of the abdomen) with six segments each and a short spike-like telson (which was the posteriormost division of the body). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the family Onychopterellidae together with Onychopterella and Alkenopterus.

Tylopterella is notable for its thick ornamentation and general body surface. Its paired tubercles or knobs in the top of its second to fifth segments differentiates it from many other eurypterids. This thickness that its body possessed is due to the highly saline conditions to which Tylopterella had to adapt in the Guelph Formation; other organisms with reinforced shells have also been found in the same place.