Anonymous said: I have a question about the Bird-Dinosaur link. How is it decided where birds begin? What are the traits that make Archeopteryx a bird but not Microraptor or Anchiornis?
Most names are now pinned to groups rather than traits (e.g. if you are the most recent common ancestor of Iguanodon and Megalosaurus or any of its descendants you are a dinosaur) and the traits that are unique to the group are inferred once you know who is related to whom.
That said, there is little agreement about where Aves (the proper name for “birds”) should go - some people think Archaeopteryx should by definition be a bird, while others (including me) think it should be restricted to the avian crown-clade, in which case Archaeopteryx wouldn’t be a bird either (and neither would enantiornithines or even Ichthyornis).
But the important thing isn’t so much where we decide to pin the name, but rather the pattern of relationships, and most phylogenetic analyses find Archaeopteryx closer to living birds than Anchiornis and Microraptor, although not all (especially Anchiornis).
The newly described “hell-chicken” Anzu, keeping its toothless beak closed up tight.
Another close-mouthed skeletal: The primitive theropod Tawa hallae, being seen rather than heard.
The newly described Torvosaurus gurneyi keeping it’s mouth shut, much as I had to the last several months waiting for it to make it into press. This image is a bit of an extra exclusive, as I probably won’t bother to post the open-mouthed version until later in the weekend.
This is not the reconstruction in the PLOS ONE paper by the way - this is my reconstruction of the skull, which differs somewhat from the modifications made in the paper.
Anonymous said: Since IIRC your formal education was in zoology, can you recomend any good book(s) on the subject?
My undergraduate degree is indeed in zoology, but that’s a very broad topic. What sort of topics are you thinking of?
Anonymous said: Skeleton of Pachycephalosaurus.
Stegoceras is the only pachycephalosaur I’ve done a skeletal of so far.
stopmonica said: Hi Scott. Do you ever do front-view illustrations of dinosaurs? An Iguanodon at my local museum seems to be missing it's sternum, and I want to know if this because they didn't have sternums, their sternums were cartilage only, or the museum has made an error. I'd like to know what the front of an Iguanodon skeleton should look like? I've been puzzling over this for a while, and haven't been able to find anything online to give me a definitive answer. Can you?
Hi Stopmonica - I do front view skeletals, but since they greatly increase the time involved in reconstructing an animal I usually only do them when commissioned. Unfortunately this has lead to most of them being either under NDA or owned by a production company (although if you happen onto my Linkedin account I have one or two up there).
As for Iguanodon, like many dinosaurs it had both a set of paired sternal plates that were bony, as well as cartilaginous elements that are usually not preserved. Many museums don’t put them up, either because they don’t have them (or casts of them), they think it will be too difficult, or in many cases I suspect it’s because it doesn’t look right (this is actually because almost all dinosaur mounts screw up the ribs and pectoral girdle placement, so it’s simply not possible to properly position the sternum).
With a properly articulated specimen, the coracoids nearly touch at the midline and sit almost directly under the neck/back juncture in the vertebral column. The paired sternal plates then can articulate with one another along the midline while also contact the inner edge of their respective coracoids.
I hope this helps!