Reconstructing Hassiavis (Patreon)

Here's one of the latest in my continuing efforts to reconstruct Eocene birds. Hassiavis is from Messel in Germany, and - as you see from the image at lower left - it's known from a complete, articulated skeleton that has all of its feathers intact. This was described by Mayr in a 2004 paper. Hassiavis appears to be an archaeotrogonid, a group of extinct birds described from the fissure fills of Quercy and (as suggested by the name) originally regarded as trogon relatives.

Based on the measurements of both the bones and the feathers, I produced the rough skeletal you see at top left. As you can make out, I actually opted to take a little bit of length off the remiges and rectrices because they looked _too long_ as measured, my thinking being that they look over-long in the fossil due to compression and decomposition. But I could be wrong on this. As is the case for many Paleogene birds, there are several ways this reconstruction could go based on assumptions made about feathering. The skull's form is known approximately, and seems to be 'globular' as goes the cranium and longish in the rostrum. Reconstruct that shape alone and you'll have something that looks like a trogon. But the fossils shows that lots of feathering is present round the bill's base (both above and below), so my thinking is that about half of the rostrum was submerged in feathers. My poor artsing skills make it look at if the bird is looking to its left, but that's not deliberate and I'll have to modify it somehow. I also made a mistake in excluding the barring that's obvious on the tail (this is because I was looking at the lower-res version of the photo included in Mayr's 2009 book at the time), so that has to be changed too.

So, what do we have? The proportions and overall look of this bird remind me of nightbirds and apodiforms a bit, which is ok since a working hypothesis on archaeotrogonid affinities is that they're part of the larger clade that includes these birds. There's also the vague facial look of a tyrant flycatcher, and indeed Mayr noted a vague similarity between the bill of Hassiavis and that of a tyrant. Overall I'm pleased with it.

Many more done or in-progress...