One of the surprising things that spexplorers noted was troodontids initially seemed absent from Spec. As a generalist, possibly omnivorous maniraptoran group known from HE Laurasia since the Late or possibly Middle Jurassic, it was hard to imagine this clade dying out completely. After closer examination, the clade had survived on Spec, in two wildly-divergent lineages on opposite ends of the earth.
Troodontids remain common in the Spec Laurasian fossil record through to the early Miocene, at which time they vanish quite suddenly. It is hypothesized that they suffered greatly from the African-Eurasian biotic interchange, which introduced vulgures, hogbirds, and mattiraptors to Laurasia for the first time. With these clades rapidly expanding into the roles of generalist omnivores and generalist small hunters, troodontids may have been squeezed in both directions, and were hard up to find competitive niches, driving them to the precipice of extinction.
Today, the only remaining troodonts are in Asia, South America and possibly in Africa. Both are so highly derived from the basal troodontid form they are of little help discerning the lifestyle of the original group.
Ibisbill Raptor (Ibidoraptor burgessae)
The 1.7 meter long ibisbill raptor is a rare, little known species found in stony, upland river valleys of the Himalayan mountains. It takes its name from the distinctive down-curved bill that superficially resembles that of the ibis. All of the teeth in its premaxillary and frontal dentary bones have been lost; however the teeth further back in the jaw form long "spikes" that allow it to hold on to slippery fish. This species possesses the enlarged inner toes of the deinonychosaurs and troodonts, however the animal uses these claws only for defensive purposes.
The ibisbill's haunting, if somewhat embarrassing call (a Shaggy-esque "ZOICKS!!!") can often be heard in the remote montane regions where it dwells. It uses its bill to probe among stones of riverbeds and rake gravel for small animals.
Though originally thought to be a "one-hit wonder" of a clade, a number of closely-related species have been reported in upland areas ranging from Asia Minor to Vietnam. They have yet to be formally described, but field observations suggest that aside from differences in plumage they are highly similar, and likely all cogeneric.
NOTORAPTORIDAE (Nandrakes and allies)
While troodontids entered a near-terminal decline in the north during the Miocene, the clade ultimately found a refuge of a sort in South America. It is thought that the ancestors of the South American troodontids migrated across a transient land-bridge from North America sometime between 75 and 65 MYA. Though initially fairly rare in the fossil record, they become omnipresent in the South American fossil record in the Oligocene as noasaurids vanish and unenlagines become rarer.
The fortunes for the South American troodontids waned, but they have retained greater diversity than their Asian brethren. The formation of the Panama isthmus and the Great Interchange three million years ago allowed mattiraptors access the continent and apparently caused the extinction of most of the small predatory troodontids. However, the omnivorous species remained intact, and even expanded into some browsing niches in the south as the climate continued to cool. Today there are roughly a dozen species ranging from chicken-sized omnivores to the largest herbivores in the South American temperate rainforest with a few roaming the lesser explored regions of Asia. As of now, reports of troodontid-like creatures thriving in Africa has been reported, but with no physical proof of their existence, this issue is still controversial to this very day.
Greater Nandrake (Notocursornis major)
The greater nandrake and lesser nandrake (Notocursornis major and Notocursornis minor) were at first quite a puzzle to systematists, because they have long lost the sickle claw of their ancestors, various skeletal details (such as the shape of the pelvis) differ appreciably from any known fossil troodontid of both timelines and don't resemble anything else either, and their DNA does not suffice to assign them to something more precise than Maniraptora. Some wondered if a weird mattiraptor had managed to cross the Atlantic Ocean; the nandrakes differ from mattiraptors, however, in their larger number of teeth, the constriction between the root and crown of these, and in peculiarities of the vertebrae. Today's consensus is that nandrakes are genuine troodontids which have survived in southern South America, although some scientists are still not entirely comfortable with this idea.
Saci (Picoraptor obscurus)
When the saci was found on the Atlantic rainforest of Brazil, it rooted the notoraptors firmly within Troodontidae. It was an unquestionable troodont, having the characteristic coarsely-serrated teeth, an intact hyper-extendable sickle-clawed toe, an arctometatarsus ankle, and a normal saurischian pelvis. It also shared unique details of the braincase and vertebrae with nandrakes and other more derived species. In many ways it is a "living fossil" which was formerly common throughout South America. Indeed, it is tempting to use the saci to make conclusions about the behavior of its Cretaceous ancestors, but a broadly similar morphology cannot be translated to identical behavior.
The saci is seldom seen in its habitat, as it is both nocturnal and coal-black, except for a shock of red feathers on the top of its head. It is far more often heard at night calling with a plaintive, sad whistle, unusually deep considering it is weighs only a kilogram. Most of its diet is made up of insects, frogs, and lizards, although stomach analyses show approximately 40% of its diet is vegetable matter, the bulk of which is fallen fruit or the berries of low shrubs.
Chonchon (Phytoraptor robustus)
With the cooling of South America, the Valdivian and Magellanic temperate rainforests of South America grew uncomfortable to lethal for native ornithischians like the viries and pachas. While various mammalian groups, including small bastardsloths and spelks, radiated into the low-browsing niches, the high-browsing niche was ultimately won by an unlikely group of purely folivorous notoraptors.
The chonchon is not the largest dinosaur in South America, weighing only 400kg. However, due to its lanky frame and long neck it can reach branches up to 5 meters off the surface of the ground-far higher than any of its competition. Its head is weirdly convergent on that of therizinosaurs, with a horny beak at the front of its jaw, simple chisel-shaped teeth in the rear, and a long dexterous tongue. Also like therizinosaurs, its pubis has become retroverted to accommodate its prodigious gut. Despite its somewhat pot-bellied frame, a healthy individual can outrun any of the hesperonychidae deinonychosaurs native to these dank forests, with its only principal enemy being the anaasazi, which often pounces on immature individuals from overhanging tree branches.
Chonchon are solitary, highly territorial, and very dangerous to humans despite their purely herbivorous nature. Individuals are highly intolerant of other chonchon outside of the mating season. When individuals do meet, they stand almost vertically, lift their tails, and trade blows with their powerful clawed forearms until one retreats. Though this fighting is fairly harmless to other chonchon, most individuals apparently confuse the form of an upright human with that of a diminutive challenger, particularly in the evenings. Should you be seen by a chonchon, it is imperative you crouch or drop onto all fours to show submission. Your life may depend on it.