My initial title for this blog was “Things that people thought were interesting fossils but turned out to be turtles”. Of course, I don’t mean that, I just have had a particularly frustrating few months reading the same undergraduate projects on turtle evolution, so they are not my favourite at the moment…. However… in the last few years, their bones seem to be popping up as being identified as other animals, which is something I found a bit amusing.
Mistaken identity 1 – the Flying turtle
|Above: plastron of Kallokibotion, with outline showing where the ‘Thalassodromeus sebesensis’ (Below) specimen would fit from Dyke et al. 2015.|
Mistaken identity 2 – Giant raptors!
Ok to be fair, this one isn’t the entire specimen, just a little bit of it, and it doesn’t change the story really. At the end of last year, a new species of giant dromeosaur was described from the Hell Creek Formation of Montana – Dakotaraptor steini . This find was significant as it was the first giant raptor from the Hell Creek Formation during the Late Cretaceous, and it had clear evidence of feather quill knobs on the ulna, the first direct evidence of feathers on the forelimbs of large dromaeosaurids. The existence of feathers on the forelimbs of a giant obviously not-flying dinosaur further supports the thought that feathers did not evolve specifically for flight, which some people have argued in the past. The new species was described from a partial associated skeleton and some additional material, including much of the forelimb, some hindlimb elements, some vertebrae, and the furculae, AKA the wishbones.
Now the difference with this find is that it was named from a significant amount of material, and most of it is just fine. However, it’s now been shown (just a few days ago by Victoria Arbour and colleagues) that the so-called “wishbones” of Dakotaraptor steini are actually part of the entoplastron of a trionychid turtle . To be fair, looking at both papers, I can see how these could have been confused, especially since I don’t work with turtles. Fortunately, in this case the initial authors appear to accept their mistake in an article written by Ed Yong. This is science at it’s best! Science works better when we can admit our mistakes and move on.
|Figure 1 from Arbour et al. 2015 showing where the entoplastron is found in trionychid turtles (A-D), and the “furculae” in question of Dakotaraptor (E-G).|
Of course there are lots of examples of fossils being misidentified. It’s bound to happen when you’re dealing with often fragmentary or distorted material, but these two examples of turtles mistaken for some extinct reptiles within the same year stuck with me. I’ve been asking for other examples, and apparently some other things like T. rex and ankylosaur bones have been misidentified as turtles in the past (thanks Dean Lomax for sharing that), and even lungfish tooth plates were thought to be turtle shell (thanks to Graeme Lloyd for that), but I wasn’t able to find any information about any of those. The interesting thing is that those are examples of people thinking they were turtles because they had never seen anatomy like that (these are from before dinosaurs and lungfish were properly understood), while the recent examples are actually turtles that are described as something else. The important thing to remember is that this is not uncommon. It happens to lots of people. The best way to avoid this is to avoid describing particularly fragmentary or poorly preserved material, and to avoid naming things if you aren’t sure, as that is much less likely to be a big deal. But we are palaeontologists who like name things…
Anyone have any other examples of things that are actually turtles? Or other amusing fossil mixups you want to share?
Since the original post, I’ve had a few other examples pointed out to me. David Evans showed me an example of some turtle phalanges originally described as troodontid pedal phalanges from Mexico, which were the only troodontid fossils known from the Cerro del Pueblo Formation, leaving no known troodontid material from this formation (see Evans et al. 2014). I was also reminded of one of the big examples of dinosaurs being mistakenly identified as turtles – Therizinosaurus cheloniformis (thanks to Logan Orlowski for pointing it out in the comments below). This bizarre dinosaur is known for it’s large claws (almost 1m long), which were originally thought to belong to a turtle-like reptile. With only the arms known, it was thought that the claws would have been just for something like harvesting seaweed in the oceans. However, we now know this is a dinosaur, and the species name cheloniformis comes from this misinterpretation, meaning ‘turtle-formed’.
1. Grellet-Tinner, G. and Codrea, V.A. 2015. Thalassodromeus sebesensis, an out of place and out of time Gondwana tapejarid pterosaur. Gondwana Research 27: 1673-1679.
2. Dyke, G. et al. 2015. Thalassodromeus sebesensis – a new name for an old turtle. Comment on “Thalassodromeus sebesensis, an out of place and out of time Gondwana tapejarid pterosaur”, Grellet-Tinner and Codrea (online July 2014 DOI 10.1016/j.gr.2014.06..002). Gondwana Research 27: 1680-1682.
3. DePalma, R.A., et al. 2015. The first giant raptor (Theropoda: Dromaeosauridae) from the Hell Creek Formation. Paleontological Contributions 14: 1-16.
4. Arbour, V.M., et al. 2015. The furculae of the dromeosaurid dinosaur Dakotaraptor steini are trionychid turtle entoplastra. PeerJ 4:e1691.