Today’s spec creature is a combination of a couple of submissions – James P. Quick asked for “a post-K/Pg relict dinosaur from pre-glaciation Antarctica”, and an anonymous asked for “a subterranean (like, say, Talpa or Spalax) burrowing dinosaur”:
At the time of the K/Pg mass extinction some of the small ornithopods that inhabited Late Cretaceous Antarctica had been developing increasingly complex burrowing behavior and a more generalist omnivorous diet than most other ornithischians – and, along with their ability to endure the long dark cold polar winters, this was juuust about enough for them to survive while the rest of their non-avian cohorts vanished.
They were very briefly a fairly successful disaster taxon in the devastated polar forests, but they were quickly displaced by other diversifying survivors and never really got another ecological foothold to regain anything close to the non-avian dinosaurs former glory.
Instead the little ornithopods specialized even further for burrowing, spending more and more of their lives underground to avoid the increasing competition and predation from mammals and birds.
Now, well into the Cenozoic at the dawning of the Miocene, Cthonireliqua quicki is the very last representative of the non-avian dinosaurs. Small and stocky and mole-like, just 15cm long (~8″), it has muscular forelimbs with large shovel-like claws, a keratinous shield on its head, and a thick bristly tail where large fat reserves are stored.
Its eyes are almost completely absent, only vestigial remnants present under the skin of its face, and it navigates its extensive burrows using sensitive whisker-like filaments and its keen senses of hearing and smell. Still omnivorous like its ancestors, it feeds on whatever it comes across while tunneling – mainly worms, insects, smaller vertebrates, roots, and tubers.
Unfortunately for Cthonireliqua, and the rest of its Antarctic ecosystem, time is running out. Over the last few million years Antarctica’s climate has been steadily cooling and drying, the continent has become fully isolated, and the Antarctic Circumpolar Current has formed. Glaciation is well underway in the continental interior, and the once-lush forests are shrinking away and being replaced with tundra.
Soon all evidence of these dinosaurs’ existence will be buried under the ice.
