Technical Session II (Wednesday, October 17, 2018, 8:00 AM) SALT GLAND STRUCTURES IN ICHTHYOSAURUS? MASSARE, Judy A., SUNY Brockport, Brockport, NY, United States of America; WAHL, William R., Wyoming Dinosaur Center, Thermopolis, WY, United States of America; LOMAX, Dean R., The University of Manchester, Manchester, United Kingdom Salt-secreting glands allow marine reptiles to remove salts that accumulate from ingesting seawater and prey that is isosmotic with seawater. Salt glands have been considered a primitive feature for diapsid reptiles. Their anatomical position varies among extant reptiles, from orbital glands in sea turtles to oral glands in marine crocodiles and snakes, to nasal glands in lizards and birds. Because of the difference in position, salt glands are thought to have originated independently multiple times. The presence of salt glands in extinct marine reptiles have been inferred from structures in the antorbital region of metriorhynchid crocodiles and narial region of mesosaurs. Additionally, paired casts of lobate structures in the internal nasal region of the Cretaceous polycotylid plesiosaur Pahasapasaurus haasi and the Late Jurassic ichthyosaur Ophthalmosaurus natans have been interpreted as evidence of nasal salt glands. Here we report the occurrence of structures in the external nares that might indicate the presence of salt gland ducts. In several specimens of the Early Jurassic ichthyosaur Ichthyosaurus (including the holotype of I. larkini), a small triangular process on the lacrimal protrudes into the external naris, defining a circular region at the posterior end of the naris. On two specimens of I. somersetensis, a ring of bone occurs in a similar position. These features might mark the position of a duct for excreting a concentrated salt solution from nasal salt glands. This is an ideal position for such a duct because the flow of water across the skull during swimming would efficiently carry away the salt solution. Poster Session (WednesdayâSaturday, October 17â20, 2018,Â