Revised May 15, 2016 with a longer neck for Tianyuanlong, more like that of its outgroup sister, Ornitholestes. Grateful to M. Mortimer for suggesting I take another look at it, but the objections raised were not valid for this taxon.
Scientific American has published several articles devoted to dinosaurs. “Rise of the Tyrannosaurs – New fossils put T.rex in its place” (Brusatte 2015) is one of the latest (Fig 1).
From the online access page:
- Paleontologists have known about T. rex and other giant tyrannosaurs for decades. But they were unable to piece together when the tyrannosaurs originated and what they evolved from because they lacked the fossils to do so.
- Recent fossil finds have gone a long way toward filling those gaps in scientists’ understanding of this iconic group.
- Together these discoveries reveal that tyrannosaurs have surprisingly deep—and humble—evolutionary roots.
- Furthermore, the group encompasses a far greater diversity of forms than experts had anticipated—including some with truly bizarre anatomical features (Fig. 2).
Despite the fantastic artwork,
the taxa in ‘the rise’ are actually basal to allosaurs and spinosaurs, not tyrannosaurs (Fig. 1), according to the large reptile tree (Fig. 4). Some of the ancestors recovered in the large reptile tree, like Zhenyuanlong, had extensive wing feathers (Fig. 3), which actually makes the ancestry of T-rex more interesting. And it makes the little hands of T-rex, vestigial wings.
Here’s the subset of the large reptile tree
focusing on basal theropods (Fig. 4). Note how Proceratosaurus, Guanlong and Dilong could be considered basal to tyrannosaurs, but really they are closer to allosaurs in this cladogram. I think the mistake may lie, once again, in taxon exclusion, but also to misinterpretation.
Brusatte S 2015. Rise of the Tyrannosaurs. Scientific American 312:34-41. doi:10.1038/scientificamerican0515-34
See a video on the production of the cover art and a peek inside the James Gurney studio here.
Learn more about artist Todd Marshall here.