Saturday, December 22, 2012

Field Guide Rejects: Arctic Troodont


Happy winter! Here's one more entry in my series of Field Guide illustrations too speculative to include in the book. It's now pretty widely known that remains attributed to the Campanian age genus Troodon have been found in the Maastrichtian age Prince Creek Formation of northern Alaska, which would have been above the arctic circle at the time. These animals have been featured in some recent TV documentaries such as March of the Dinosaurs. Though the remains are fragmentary and mostly undescribed, the fact that they are later in age than Troodon formosus, and in some cases twice the size of comparable T. formosus remains, it's a near certainty in my and others' opinions that these represent a new species if not genus of troodontid.
Restoration of hypothetical winter & summer plumage in the
unnamed Prince Creek troodontid species, by Matt Martyniuk.
A staple of field guides to modern birds is to illustrate seasonal differences in plumage, which are widespread in cold climates. Of course, we don't currently have any information on plumage variation in Mesozoic birds, but the fact that this is one of the few Mesozoic species that may have regularly encountered snow made it too hard to resist adding this additional layer of speculation.


  1. I think Dinosaur Train featured these guys as well.

  2. An Arctic troodont? I never knew that troodontids lived in Alaska. The fact is that while the genus Troodon has been recorded from Alaska (see Weishampel et al 2004 for dinosaur records from Alaska), the long timespan for Troodon formosus makes it unlikely that the Arctic troodont is the same species as Troodon formosus. The taxonomic identification of most theropod specimens from Alaska to generic level is only tentative and is subject to change when partial theropod skeletons are found in the Prince Creek Formation.


  3. I completely agree that the Alaskan troodonts will most likely end up being a new species, if not a new genus.

    I actually noticed something peculiar about the Alaskan troodonts. The anatomy of their teeth is different from Troodon formosus. T. formosus has serrations on both sides of its teeth, while the Alaskan troodonts have serrations only on the posterior side. In this respect, they are similar to Saurornithoides mongoliensis and Zanabazar junior, who also have serrations on only the posterior side of their teeth.

    Therefore, I hypothesize that the Alaskan troodonts might be relatives of Saurornithoides or Zanabazar that crossed the Bering land bridge and increased in size. Since the Alaskan specimens are the largest known troodontids, and Zanabazar is the largest troodontid besides the Alaskan ones, it makes sense that Zanabazar or one of its close relatives could have crossed the Bering land bridge and evolved into the Alaskan troodonts.

    Perhaps the Alaskan troodonts are more closely-related to Zanabazar and Saurornithoides than the more southern North American troodontids, such as T. formosus. More research is definitely needed to clear up this whole situation.

