Over 50 long time ago , researchers unearthed 300 - million - twelvemonth - old fossils of a mysterious , soft - embodied creature from a coal minelaying pit in Illinois . They called it the " Tully colossus , " after dodo aggregator Francis Tully who discovered it , and in 1989 , it was designate the official res publica fossil . Ideas about what it could be array from a slug - like critter to a Pisces the Fishes relative . Now , harmonize to researchers hit the books more than a thousand of these specimen , this mysterious little monster is in spades a vertebrate . It ’s close pertain to jawless Pisces the Fishes calledlampreys . The findings are issue inNaturethis calendar week .
" I was really surprised when I realized the Tully monster was a vertebrate ! " Yale’sVictoria McCoytells IFLScience . " It ’s really rarified in the fossil record to have a vertebrate without bones or other hard tissue , so it was definitely unexpected . " base on its shape and complex body part , the dodo has antecedently been linked to worms , shellfish ( like snails and shekels ) , arthropods ( which includes insects and spiders ) , andconodonts , which is an extinct chordate . Chordata is the phylum that all craniate go to , and all chordate have a skeletal rod called a notochord . In human being , this goes on to become part of our prickle .
One of the well - supported theory was that it was a conodont , and with that in nous , McCoy and colleague analyzed more than 1,200Tullimonstrum gregariummuseum specimen expose from later Carboniferous Mazon Creek sediments dating back 307 to 309 million years .
Holotype ( metal money - define ) fossil of Tullimonstrum gregarium , the " Tully lusus naturae . " This specimen has the best preservation of morphological characteristic , admit muscleman segments in the dead body , the eye bar , the tail fin , and the proboscis and jaw folded back over the body . Paul Mayer / Field Museum of Natural History
They reinterpreted the two - dimensional , light - colored complex body part present length - heady in the fossils as a notochord . It was previously conceive to be the trace of a gut . The 10 - centimeter - long ( 4 - column inch - farsighted ) animal also has gill , a metameric body , eyes projecting from the ending of a farseeing rigid bar ( like in hammerhead sharks ) , a jaw setup containing small pointy tooth at the end of a trunk - like trunk , and a fag end louvre . This combination of features – together with an psychoanalysis of its evolutionary relationships – hint that the brute is a craniate .
what is more , the Tully monster is close link up to today ’s lampreys , but it ’s not quite their ancestor . " If you think of the lamprey family tree as an actual Sir Herbert Beerbohm Tree , all living lampreys are up near the top , in the crest where all the leave-taking are , " McCoy explains . " The ancestor of modern lampreys are on the trunk , the right way near the top where it begin branching out into the leafy part . However , there are trivial branches come out of the trunk , below the antecedent of all modern lampreys , and these are the stem lamprey eel , including the Tully goliath . "
reconstructive memory of the Tully monster . Notice the jointed proboscis , the multiple rows of teeth , and the dorsal heart stripe . Sean McMahon / Yale University
