#bathornis cursor

By Ripley Cook

Etymology: Tall Bird

First Described by: Wetmore, 1927

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, Australaves, Cariamiformes, Bathornithidae

Referred Species: B. celeripes, B. cursor, B. fax, B. fricki, B. geographicus, B. grallator, B. minor, B. veredus

Status: Extinct

Time and Place: From 37 to 20 million years ago, between the Priabonian of the Eocene of the Paleogene and the Burdigalian of the Miocene of the Neogene 

Bathornis is known from a very wide number of formations - which makes sense, given how many species have been referred to the genus. Bathornis is known from the Chadron Formation, the Brule Formation, the Willow Creek Site (not Formation, that’s from the Cretaceous because people keep reusing names), the Washakie Formation, and the Willwood Formation - and it is possible that it is also known from other locations throughout North America. It appears to have concentrated on the western half, however, being known from formations in Colorado, Nebraska, South Dakota, and Wyoming. 

Physical Description: Bathornis was a large, flightless predatory dinosaur from the Cenozoic - and, despite being in the same general group of birds as they, it isn’t a terror bird! Bathornis, unlike the Terror Birds, still had decently sized wings (even though they couldn’t be used in flight) and, more importantly, it had a well-developed hind toe, whereas the Terror Birds had reduced hind toes. Still, it was doing essentially the same thing, but in North America. It had long, thin legs, built well for running; a squat body; small-ish wings; reduced musculature in the shoulder and chest area; large heads, and long, sharp beaks. These beaks weren’t as tall as those found in the Terror Birds, but that didn’t take away from their ability to pack a devastating bite. The variety of species ranged widely in size, with some as short as 60 centimeters, and some as tall as 2 meters (though it is possible the smaller species were just juveniles).

By Julio Lacerda

Diet: Bathornis was a terrestrial carnivore, able to utilize its large beak to grab and crush large prey - even large mammals. It is even possible that in many environments, Bathornis was one of the primary large predators, similar to the Terror Birds of the south.

Behavior: Bathornis, being a very large terrestrial predator, would have spent a good portion of its time on the move. Its long, strong legs were good for running, as well as probably kicking. Not being able to fly, they would have relied on their legs to get around and chase prey. Powerful kicks of the legs would have aided Bathornis in killing its prey, however, it would have primarily relied upon its beak to deliver the final blows. The powerful crushing action of the beak would have allowed it to break apart extremely tough prey, potentially even crushing bone. It may have still used its wings in some flapping action to aid in hunting, though it doesn’t seem likely it used them as much as the earlier terrestrial raptors of the Mesozoic era. Being a predator, it doesn’t seem likely that Bathornis was very social; modern Seriemas hunt primarily alone, and there’s no evidence Bathornis did otherwise. Still, it probably did care for its young in some capacity. 

By Nix, CC BY-NC 4.0 

Ecosystem: Bathornis is known from a variety of ecosystems across Northwestern America in the Cenozoic Era; it seems, however, it favored wetlands to open savanna and grassland. It may have also been found in more sparse woodland. This means that, while it was fast, running great distances across open habitat wasn’t its usual activity. It may have even used its long legs to aid in wading through the water towards sources of food. That doesn’t mean it never inhabited open areas, of course - just that it probably preferred bogs and swamps to prairies. Bathornis often lived alongside large mammals, including large mammalian predators such as Haenodonts, Entelodonts, and Nimravids. Odd-toed ungulates like Megacerops and Merycoidodon were often found closely associated with Bathornis, indicating that they were common sources of prey for this dinosaur. It also was often found with its close relative, Paracrax, which would have been direct competition for it. Many other dinosaurs are known to have lived alongside Bathornis, more than I can reasonably list; but it probably encountered the fowl Procrax, the flighted predator birds Phasmagyps and Palaeoplancus, the tody Palaeotodus, the flighted ratites Lithornis and Paracathartes, the large herbivorous bird Gastornis, the flightless wading birds Geranoides and Palaeophasianus, the owl Eostrix, the mousebirds Anneavis and Eobucco, and the Sandcoleid sandcoleus. It’s interesting that Bathornis quite probably encountered Gastornis, given that Gastornis used to be thought to have Bathornis’ job, and is now known to have been a similarly-sized large herbivore instead. 

By José Carlos Cortés

Other: Bathornis was very closely related to the contemporaneous (but Southern) Terror Birds, but it actually evolved for the same niche independently. This happened all over their group of dinosaurs, the Cariamiformes (Seriemas and their many, many extinct relatives). This indicates that the long-legged terrestrial predatory lifestyle of the Seriema group made them especially prone to growing larger, and losing their flight capabilities. The common nature of Bathornis and its relatives in the Northern Hemisphere is also important biogeographically. Many think that the Terror Birds went extinct due to the influx of large mammal predators after North and South America combined. However, Bathornis lived alongside these North American Large Mammals - and even thrived in its environment. So, clearly, large avian predators and large mammalian predators were perfectly capable of coexisting. So why did Bathornis - and then, later, their southern Terror Bird cousins - go extinct? Jury is, sadly, still out. 

By Scott Reid

Species Differences: There are a wide variety of species of Bathornis, though some may not be the same species, and it is entirely possible that these animals shouldn’t be grouped under one genus from a phylogenetic standpoint. B. veredus is known from the Eocene and Oligocene of the Chadron Formation, and was about the size of a living emu. B. cursor is different from B. veredus primarily because of differences in the ankle, and it was slightly larger and earlier in time. B. geographicus is known from South Dakota, Nebraska, and Wyoming, and it may be a descendant of B. veredus; it was larger than both veredus and cursor, and it is possibly the largest species in the genus. B. fax is the smallest species known, but it also lived with B. veredus and is probably just the juvenile form. B. celeripes is known from the end of the Oligocene, and it was about the same size as B. cursor, so a mid-sized species of the genus. B. fricki is from the Early Miocene, making it one of the youngest species of all; it may have been a direct descendant of B. celeripes, to which it was very similar. B. minor lived in the same time and place as B. fricki, and they differ due to small changes in the leg bones. B. grallator, finally, is the best known form; coming from the Eocene, it was originally called Neocathartes before being combined into Bathornis by Mayr in 2016. It was originally thought to be flighted, but further research has shown it was also flightless. It was actually first thought to be a vulture! Life is funny like that.

~ By Meig Dickson

Sources under the Cut