''Seldsienean'' (

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...

for "seldom seen one") in an extinct genus of

machimosaurid Machimosauridae is an extinct family of teleosauroid thalattosuchian crocodyliforms. Text was copied from this source, which is available under Creative Commons Attribution 4.0 International License The family was first identified in 2016, ...

thalattosuchian from the

Middle Jurassic The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations co ...

of England and France. It is known from the Calcaire de Caen and the

Cornbrash Formation The Cornbrash Formation is a Middle Jurassic geological formation in England. It ranges in age from Bathonian to Callovian, the uppermost part of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from the forma ...

. Its type species, ''S. megistorhynchus'', was originally described as a species of '' Steneosaurus'' in 1866, but was given its own genus in 2020.

References

Thalattosuchians Fossil taxa described in 2020 Prehistoric pseudosuchian genera {{Paleo-archosaur-stub