Sallan, Giles, Sansom, Clarke, Johanson, Sansom, and Janvier, 2017, The ‘Tully Monster’ is not a vertebrate: Characters, convergence and taphonomy in Palaeozoic problematic animals: Palaeontology, p. 1-9.
What’s it about?
The “Tully Monster” (Tullimonstrum gregarium) is a fossil originally described from Carboniferous coal deposits near Mazon Creek, Illinois. It is also known from localities in western New York State, including Taughannock Falls near Ithaca. There has been a lot of discussion about what the Tully Monster is most closely related to (e.g. worms, arthropods, or vertebrates). In 2016, two papers were published that asserted that Tullimonstrum was a vertebrate. The authors here show why that interpretation is in error.
Why does it matter?
Our interpretation of vertebrate, chordate, annelid, arthropod, etc has an effect on how we define ‘vertebrate’ and how we interpret fossils that are little more than stains on rock in the fossil record. The challenge here is immense. The authors show that if one draws conclusions that require the least amount of explaining away weird preservational effects, the only possible conclusion is that Tullimonstrum cannot be a vertebrate, but could be closely related to the chordates.
Why did I read this?
This is required reading for my vertebrate paleontology course this semester. Plus, it’s simply interesting.