#oligocolius

As the global climate was cooling during the Oligocene epoch, tropical rainforests started to shift towards their current distribution in the tropics, and open landscapes such as scrubland was spreading. But that doesn't mean forests were disappearing. In places like Central and Eastern Europe, forests shifted from tropical to temperate. And in these shifting landscapes, birds continued to adapt and diversify.

Turnipax: One of the earliest known members of a relatively obscure bird groups called buttonquails. Despite their quail-like appearance and lifestyle, buttonquails are shorebirds related to gulls and sandpipers.

Palaeotodus: This small insectivore is one of the first known members of the todies, a bird group nowadays restricted to the West Indies.

Primotrogon: An early member of the trogons which had a very different shape compared to its modern relatives, including long wings, a short tail, and relatively small eyes.

Eurotrochilus: The first known true hummingbird, a group now endemic to the Americas, but first appeared in Europe.

Aviraptor: A thrush-sized true hawk with long thin legs and sharp talons, this was a prime predator of small forest birds in the Oligocene.

Wieslochia: One of the earliest known passeriformes, a group that likely evolved in Australia,parts of it's skeleton resemble certain South American passeriforms, like cotingas.

Rupelramphastoides: As the earliest known ramphastid, it was closely related to the barbets as well as toucans, but it bore a closer resemblance to the former.

Oligocolius: A bizarre relative of modern mousebirds that had an appetite for seeds, as the holotype was preserved with seeds in its crop and gullet. It also had a slightly parrot-like beak.

Laurillardia: A distant relative of hoopoes and hornbills, this long winged and long tailed bird used its sharp beak to catch insects.

By José Carlos Cortés

Etymology: Oligocene Mousebird

First Described By: Mayr, 2000

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoromorpha, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Averaptora, Avialae, Euavialae, Avebrevicauda, Pygostaylia, Ornithothoraces, Euornithes, Ornithuromorpha, Ornithurae, Neornithes, Neognathae, Neoaves, Inopinaves, Telluraves, Afroaves, Coraciimorphae, Coliiformes, Coliidae

Referred Species: O. brevitarsus, O. psittacocephalon

Status: Extinct

Time and Place: Between 31 and 24.7 million years ago, from the Rupelian to the chattian of the Oligocene 

Oligocolius is known from the Bott-Eder Grube Unterfeld and the Enspel Maar Lake of Germany 

Physical Description: Oligocolius is a fascinating little bird because it is a Mousebird - a group of dinosaurs today with magnificent little crests and soft, grey appearances - but, in at least one species, it didn’t have a typical Mousebird beak. Instead of having a short, triangular beak, this bird had the dramatically hooked bill of a parrot! With a large, round head and a hooked, sharp beak, it would have been very hard to tell apart Oligocolius from a living parrot when just looking at the head. This is a clear-cut case of convergent evolution, since mousebirds and parrots are nowhere near closely related to each other. Oligocolius was weird in other ways too - it had longer wings than living Mousebirds, and shorter legs, so it was more adapted for flight than living members of the genus. Interestingly enough, it also seems to have had a crop, which is something living Mousebirds lack; this indicates that it fed on tougher to digest plant material than Mousebirds today do - meaning, it wasn’t only eating fruit like its living relatives. Instead, it was able to eat tougher to digest plant material in addition to fruit. Whether or not its feathering would have been as weird as its living relatives is difficult to say without more fossils. It is difficult to say what its size would have been, as no tail feathers are preserved and the mousebirds today are distinctive for their long tails, but it seems likely they were about as big as living forms, reaching sizes around 10 centimeters in length.

Diet: Oligocolius would have fed on a variety of plant material, rather than exclusively fruit; in addition to fruit, it probably would have favored seeds, which it could easily crack open with its parrot-like beak.

Behavior: Oligocolius would have flown too and fro in its forested environment, searching for food and spending less time perched than its living relatives. It would probably gather seeds, fruit, and other plant material from trees as it flitted about, holding and crushing the food with its strong beak. Despite being rare in terms of fossils, it was probably very social like its living relatives, forming somewhat large family flocks in the forests. It would have taken care of its young, even potentially building cup-shaped nests out of twigs in trees. It is probable that it would have been very distinctive in appearance, as its living relatives are, and used that appearance for communication. 

By Scott Reid

Ecosystem: Oligocolius was probably a fairly common fixture of the forests of the Oligocene in Germany, having been found in two different environments from across the epoch. It is known from primarily forested areas near bay and estuary coastlines, as well as a prehistoric freshwater lake with a variety of shore plants and swamps, so it wasn’t picky about where it ended up. O. brevitarsus, in the earlier Bott-Eder environment, it lived alongside many different kinds of birds that I’ve mentioned in articles past: the hummingbird Eurotrochilus, the barbet Rupelramphastoides, the trogon Primotrogon, the loon Colymboides, the seabird Rupelornis, the songbird Wieslochia, the tody Palaeotodus, and the buttonquail Turnipax. There were also a variety of mammals. At the later Enspel swamp-lake, there were rodents like Eomyodon, pikas, and moles, as well as crocodilians and turtles; as for other birds, there was the pheasant Palaeortyx, the cormorant Borvocarbo, and a loon.

Other: Oligocolius is closely related, but not entirely in, the group of living mousebirds. In fact, Oligocolius is one of many known extinct mousebirds, showcasing that this group was much more diverse in the past than it is today. The weird parrot-like beak of Oligocolius is just one of many evolutionary paths the mousebirds took during the Cenozoic era.

Species Differences: O. brevitarsus is the first described species of this genus, and does not have an associated head; thus, it cannot be said with any certainty that it had the parrot beak, though that does seem likely. It comes from earlier and more southward than O. psittacocephalon. O. psittacocephalon, in addition from being later in time and a more northward location, it also had differently proportioned limbs than its earlier cousin.

~ By Meig Dickson

Sources under the Cut 

Today, mousebirds are a group of six African species. During the Paleogene, however, they were far more diverse, and were prominent in European and North American ecosystems.