Pulmonoscorpius
Pulmonoscorpius kirktonensis (from Latin pulmonis scorpius, 'lung scorpion') is an extinct species of scorpion[1] that lived during the Viséan and Serpukhovian ages of the Carboniferous period, around 336.0 – 326.4 million years ago.[2]
The name derives from "Latin pulmonis, a lung, and Greek skorpios, a scorpion."[2] The Latin suffix -ensis means "of or from a place."
Its fossils were found in the East Kirkton Limestone at East Kirkton Quarry, West Lothian in Scotland. It dates to the Carboniferous.[3]
The diet of Pulmonoscorpius is not known directly, but it is probable that it preyed on smaller arthropods, and small tetrapods (new arrivals).[4]
Most complete specimens were 13–280 mm (0.51–11.02 in) in length, while a large, fragmentary specimen is estimated to have been 700 mm (28 inches) long when alive. The only portions preserved were the outer portions of the cuticle, estimated to only be 15-18 μm thick in the largest specimen.[2]
Pulmonoscorpius is characterized by the presence of a long spur on each of the apophysis (extension of the coxa, the basalmost segment) of the 1st leg pair, 1st ventral abdominal plate of juveniles with median lobation, as well as an elongated sternum (ventral plate between the leg bases) with Y-shaped sulcus.[2] Unlike modern scorpion but similar to other basal counterparts, Pulmonoscorpius possess a pair of anterior-positioned median eyes and a pair of lateral eyes that between 40 and 60 lateral ocelli may be present in each of them, as well as a last (5th) metastomal segment with length did not exceed the preceding 4th metastomal segment.[2] The surface of prosomal carapace and 7 mesosomal tergites are relatively smooth in juvenile while tuberculated in larger individual.[2] The chelicerae and legs were noted be to be similar to those of extant scorpions, except the coxae and femurs (1st and 3rd segments) in legs 3 and 4 are less elongated, and the tibiae of these legs are about the same length as their femora.[2] The femur and patella (4th segment) of each pedipalp, as well as each metasomal segment possess ridges lined up by rows of tubercles.[2] The mesosoma possessed a bilobed and laterally elongated genital operculum (covering of gonopore), pectines (comb-like sensory appendages) with 150-160 narrow teeth,[2] as well as 3 ventral plates in juveniles and 4 in adults.[2] As with modern scorpions, four pairs of book lungs were present at the corresponding ventral plates.[2]
