Longmornis robustirostrata

By Scott Reid

Etymology: Longmore’s Bird

First Described By: Boles, 1999

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Averaptora, Avialae, Euavialae, Avebrevicauda, Pygostylia, Ornithothoraces, Euornithes, Ornithuromorpha, Ornithurae, Neornithes, Neognathae, Neoaves, Australaves, Psittacopasserae, Passeriformes, Eupasseres, Passeri, Euoscines, Corvides, Orioloidea, Oriolidae  

Status: Extinct

Time and Place: Between 23 and 16 million years ago, from the Aquitanian to the Burdigalian of the Miocene  

Longmornis is known from the Fauna Zone B of Riversleigh in Australia  

Physical Description: Longmornis was a bird that was practically a modern sort, within the group of living Orioles and possibly nested firmly in this group. However, this hasn’t been tested (as far as I can find) via phylogenetic analysis, so take that with a grain of salt. Longmornis was a mid-sized perching bird, about 32 to 34 centimeters in length. It had a broad, triangular beak, which was curved downward. This is very similar to the living Figbirds, a group of Orioles also from Australia. However, the only bit of Longmornis that has been found is the jaw, so the rest of its body shape is uncertain; it would have been small, with skinny legs for perching in trees, like the rest of its group. 

Diet: The shape of the bill indicates that Longmornis was a frugivore, like the living Figbirds it seems to be closely related to. 

Behavior: Longmornis would have behaved similarly to living passerines – spending most of its time perching in trees, scouring the branches and the forest floor for fruit to eat. Like living Orioles, it probably would have stuck to the canopy, mostly in more open parts of the forest, though it may have stuck to the dense forest areas. The breeding behaviors can’t exactly be determined, especially since the Orioles Longmornis resembles the most are Figbirds – while most Orioles are territorial monogamous breeders, the Figbirds breed in loose colonies. As such, it is possible that Longmornis bred in either of those ways; it did, however, take care of its young. 

Ecosystem: Longmornis lived in the famed Riversleigh fauna, a diverse Paleogene – Neogene transitional ecosystem from Australia as it changed from a dense rainforest to a more open, arid shrubland as found today throughout Australia. Longmornis, however, lived earlier, while this environment was still a very dense forest. This is an important fossil site mainly because it showcases how the weird mammals of Australia evolved during the Cenozoic. Here there were monotremes, a million marsupials, bats, and a tree-dwelling crocodile Trilophosuchus, as well as many other lizards, crocodilians, and snakes. Birds were extremely common too – the lyrebird Menura tyawanoides, the corvid-sized Corvitalusoides, a bird of prey Pengana, an unnamed Cockatoo, the logrunner Orthonyx, the sittella Daphoenositta, the cracticine Kurrartapu, and many more – making Longmornis one of many birds diversifying in this lush habitat. 

Other: Since Longmornis hasn’t been tested in a phylogenetic analysis, and it also is only known from the one beak, its assignment as an Oriole is a bit of a misleading one. This was done from a more qualitative analysis rather than a quantitative one, so it must be taken with a grain of salt. That being said, Longmornis does resemble the living Figbirds to some extent; it is entirely possible that it is closely related to that group’s ancestor. This jaw is also notable because, frankly, songbirds don’t fossilize well, and jaws and skulls fossilize even worse. So, further study of the skull of Longmornis may aid more in understanding the diversification of this extremely speciose group of dinosaurs, the songbirds. 

~ By Meig Dickson

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