In 1997, Polish palaeontologist Gerard Gierliński worked together with artist Marta Szubert to create the amazing furry green(ish), life-sized Dilophosaurus model you see here (and below), nicknamed Dyzio. It was displayed at the Polish Geological Institute’s Geological Museum at Warsaw and, while much discussed in the Polish media, is poorly known internationally.
Yes, there are a few inaccuracies (the hands are palms-down, rather than shown with the inwards-facing palms that are more correct), but overall it’s a pretty neat looking model, and it’s also bold and daring. What led Dr Gierliński to create this starling vision? As we’ll see, an interesting and controversial fossil led Gierliński to argue that big early theropods like this really were covered in fur-like feathering…
We now know without doubt that coelurosaurs – the theropod dinosaur group that includes tyrant dinosaurs, ostrich dinosaurs and maniraptorans – were feathered. The more basal coelurosaurs (like tyrants) had simple, quill-like ‘proto-feathers’ on their bodies, while the more bird-like maniraptorans (dromaeosaurs, oviraptors and so on) had complex, vaned feathers on their limbs and tails at least. At the moment, we have very little data on the integument of non-coelurosaurian theropods, so one of the big questions is: how widespread were such structures within Theropoda as a whole? Were baby allosaurs and megalosaurs ‘feathery’, and what about small and juvenile ceratosaurs and coelophysids? The recent discovery of quill-like integumentary structures within ornithischians (like the heterodontosaurid Tianyulong, shown here), combined with their presence in pterosaurs, has made it seem all the more likely that these structures were present throughout Dinosauria (and Ornithodira?), though uncertainty and argument remain [photo below courtesy of Andy Wolniewicz].
It’s relatively little known that a fossil track from the Lower Jurassic Portland Formation of Massachusetts has been interpreted by some as revealing evidence for a feathery pelage in…. shock horror…. a large dilophosaurid. You don’t have to be a dinosaur expert to know what dilophosaurids are: everyone these days is familiar with Dilophosaurus, a large (c. 6 m long), slender theropod famous for its paired, plate-like head crests (it was depicted, for no reason whatsoever, as a hopping, venomous pygmy theropod with a short skull, neck frill and ability to spit thick blinding venom, in the movie Jurassic Park [its 'ancestor' - Crichton's book version - was also in the habit of spitting venom, but at least it looked like the real Dilophosaurus]).
The Portland Formation track (known either as AC 1/7 or as PMNH-EHC 1/7*) is not a new discovery: it’s one of Edward Hitchcock’s finds from the 19th century, and was acquired between 1858 and 1865 when Hitchcock named it Anomoepus major [the fossil is shown below, together with Gierliński's interpretation of it]. Hitchcock considered the trackmaker as a marsupial at times, and as a bird at others (remember that, when he was writing, we were at a very early stage in our knowledge of Mesozoic tetrapod diversity). Most modern workers have regarded Anomoepus tracks as the products of ornithischians. Today it’s obvious that AC 1/7 was produced by a large theropod; it can’t be regarded as an Anomoepus track therefore and was identified by Gierliński (1996) as belonging to Grallator minisculus. Grallator tracks were made by theropods, and some of these trackmakers were large, by which I mean 5 m long and more. At least some of the larger Lower Jurassic Grallator tracks were quite probably produced by Dilophosaurus. Martin & Rainforth (2004) have since argued that AC 1/7 is instead better referred to Fulicopus lyellii (the taxonomy of Grallator, Eubrontes and similar ichnotaxa is very confusing and I think that this name is likely incorrect. I’m going to avoid this whole mess, but feel free to elaborate in the comments if you have time).
* AC = Amherst College. PMNH = Pratt Museum of Natural History at Amherst College.
Feather impressions in a big, early theropod?
AC 1/7 is very interesting: it’s a squatting trace, made when the animal placed its belly, pelvis and metatarsi in contact with the ground. Theropod ‘resting traces’ of this sort have been reported from elsewhere (Lockley et al. (2003) provided a review), the best known and best preserved being the amazing Moenave Formation tracks from Utah, described recently by Andrew R. C. Milner and colleagues (Milner et al. 2009). What makes AC 1/7 unusual is that there are peculiar ‘feathery’ markings located around the sides of the belly and foot impressions.
What could these represent? Gierliński (1996, 1997, 1998) and Kundrát (2004) identified these as feather impressions, and argued that here was evidence for the presence of a feathery pelage in a large, Early Jurassic theropod. Pretty incredible if true: Gierliński wrote of his reluctance to share this hypothesis without becoming thoroughly convinced of its reality (Gierliński 1998, p. 3). By pressing modern feathers into soft substrates, and by looking at resting traces produced by large birds (such as an Andean condor Vultur gryphus at Warsaw Zoo), Gierlinski concluded that the trackmaker was indeed covered with a feathery integument where the structures were ‘more flexible than scales, thinner than flight feathers, and broader than mammalian hairs. Probably they were similar to the furry feathers of flightless birds’ (Gierliński 1996, p. 183). Kundrát (2004) compared the feathery impressions of AC 1/7 with the down of ratite chicks, and also concluded that the AC 1/7 trackmaker was most likely covered by filamentous, ratite-like feathers [image of Dyzio below from here].
Well, so far so good. But you’d be forgiven for being sceptical. Does the impression really demonstrate the existence of a furry/feathery pelt in Dilophosaurus (or, at least, in a Dilophosaurus-like theropod)? Both Gierliński and Kundrát argued that the impressions didn’t match with the drag marks sometimes made in the mud around large animal tracks, and hence insisted that they were produced by structures attached to the animal’s body.
However, other palaeoichnologists (palaeoichnology = the study of ancient tracks), including Paul Olsen, Ray Stanford and Emma Rainforth, have stated that the impressions are far more likely to be sedimentological artefacts. An idea once considered for the traces is that they were caused by vegetation dragging across damp mud. Martin & Rainforth (2004) have since argued that they’re ‘pressure release’ structures caused by the movement of the animal as it shifted its weight when rising up after resting: as it did so, the sediment deformed into a pattern of tiny ridges and grooves, and it’s these that have created the look of feather-like structures.
Is Martin and Rainforth’s argument any more realistic than Gierliński’s, or Kundrát’s? I find their explanation more convincing, and I also can’t help but be swayed by the fact that more workers have favoured the ‘artefact’ explanation than have favoured the ‘feather’ explanation. It’s a shame really, as the idea that Dilophosaurus was decorated by a sort of ratite-like furry feathering is obviously cool. But, as Martin & Rainforth (2004) stated, even if the ‘artefact’ explanation is correct, the possibility of feathers in early, non-coelurosaurian feathers is not precluded. We need more evidence.
My initial plan with this ‘article’ was simply to post the photos of Dyzio and accompany them with a few tens of words (by the way, this article contains more images of Dyzio than any other place on the web, so far as I can tell). Alas. And, incidentally, this was all inspired by something altogether different that I hope to discuss some time over the next few days. Things here are kinda busy though… [photo below courtesy of Andy Wolniewicz; thanks again Andy].
For other articles on feathered non-avian theropods, see…
- Feathers and filaments of non-avian dinosaurs, part I
- Feathers and filaments of dinosaurs, part II
- My old, sad t-shirt (‘Scaly protobirds no thanks!’)
- Epidexipteryx: bizarre little strap-feathered maniraptoran
- Long and Schouten’s Feathered Dinosaurs, a review
- A month in dinosaurs (and pterosaurs): 1, therizinosauroid fuzz
- A month in dinosaurs (and pterosaurs): 2, of alvarezsaurids and avialians
- The ‘Birds Come First’ hypothesis of dinosaur evolution
- Birds Come First – oh no they don’t!
- Babies love Luis Rey
And here’s some more Dyzio, this time from wikipedia.
Refs – -
Gierliński, G. 1996. Feather-like impressions in a theropod resting trace from the Lower Jurassic of Massachusetts. Museum of Northern Arizona Bulletin 60, 179-184.
- . 1997. What type of feathers could nonavian dinosaurs have, according to an Early Jurassic ichnological evidence from Massachusetts? Przegląd Geologiczny 45, 419-422.
- . 1998. The furry dinosaur. Dinosaur World 4, 3-5 [author's name mis-spelt 'Geirlinski'].
Kundrát, M. 2004. When did theropods become feathered? – evidence for pre-Archaeopteryx feathery appendages. Journal of Experimental Zoology (Mol. Dev. Evol.) 302B, 355-364.
Lockley, M., Matsukawa, M. & Li, J. 2003. Crouching theropods in taxonomic jungles: ichnological and ichnotaxonomic investigations of footprints with metatarsal and ischial impressions. Ichnos 10, 169-177.
Martin, A. J. & Rainforth, E. C. 2004. A theropod resting trace that is also a locomotion trace: case study of Hitchcock’s specimen AC 1/7. Geological Society of America, Abstracts with Programs 36 (2), 96.
Milner, A. R. C., Harris, J. D., Lockley, M. G., Kirkland, J. I. & Matthews, N. A. 2009. Bird-like anatomy, posture, and behavior revealed by an Early Jurassic theropod dinosaur resting trace. PLoS ONE 4(3): e4591. doi:10.1371/journal.pone.0004591