Cancrinos

Did You Know?

• Reinhard Förster proposed in 1984 that Cancrinos was a transitional form between spiny lobsters (Palinuridae) and slipper lobsters (Scyllaridae).
• It is unclear whether the smallest specimens of Cancrinos are in the puerulus stage or are juveniles.

Taxonomy

Fossils of Cancrinos are rare and often imperfectly preserved. Count Georg zu Münster first described the genus in 1839 from the Upper Jurassic Solnhofen limestones of southern Germany, naming two species, Cancrinos claviger and C. latipes, based on differences in the size of the second antennae; these are now considered synonyms. Additional specimens from Upper Cretaceous lithographic limestones of Lebanon were described as a new species, C. libanensis, but Haug et al. (2016) made it the type species of a separate genus, Paracancrinos.

Description

The second antennae of Cancrinos are its most distinctive feature, flattening near the tips much like those of modern slipper lobsters. However, unlike living slipper lobsters, these flattened sections retain many small segments instead of being fused into a single piece. Younger specimens have antennae that are less flattened, resembling those of spiny lobsters. This change over the animal's growth is a type of heterochrony called peramorphosis. Scientists believe this development mirrors Cancrinos' evolutionary history, showing a partial shift from an ancestral spiny lobster-like form toward a more derived slipper lobster-like form.