Gillicus

This genus contains two known species: • †G. arcuatus (Cope, 1875) - Turonian to Santonian of Kansas (Niobrara Formation), South Dakota (Benton Shale), and Utah (Tropic Shale), US, Turonian of Coahuila, Mexico • †G. serridens (Woodward, 1901) - Albian of England (Gault Formation) An indeterminate Gillicus species is known from a nearly complete skeleton recovered from the Early Maastrichtian of the Izumi Group, Japan, representing one of the latest records of the genus. A partial ichthyodectiform skull reminiscent of either Gillicus or Chiromystus was recovered from earliest Cenomanian-aged rocks in a drill core taken from the Cape Verde Rise in the southern Atlantic Ocean, about below the surface. == Description ==

Like its larger relative, Ichthyodectes ctenodon, Gillicus had numerous small teeth lining its jaws, and ate smaller fish by sucking them into its mouth, but the teeth of Gillicus are so small that the jaws appear almost toothless at first, which has led to the suggestion that Gillicus was also a filter-feeder. The Gillicus bones have not been digested so the larger fish must have died soon after eating its prey. The cause of death may have been due to injuries, such as a ruptured major blood vessel, caused by the fin of the smaller fish as it struggled while being swallowed. Nearly all of the Gillicus specimens collected from the Smoky Hill Chalk are adults or subadults, which suggests that the early stages of their life were spent elsewhere. In 2021, the children's book ''The Plesiosaur's Neck coined the common name "pug fish" for the Gillicus''. ==References==