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Concavenator corcovatus

By Scott Reid 

Etymology: Cuenca Hunter

First Described By: Ortega et al., 2010

Classification: Dinosauromorpha, Dinosauriformes, Dracohors, Dinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Carnosauria, Allosauroidea, Allosauria, Carcharodontosauria, Carcharodontosauridae

Status: Extinct

Time and Place: 125 million years ago, in the Barremian age of the Early Cretaceous 

Concavenator is known from the Unit 3 of the Las Hoyas site of the La Huérguina Formation in Castile La Mancha, Spain 

Physical Description: Concavenator was a weird dinosaur for a variety of reasons. While it could have been just your usual Carnosaur - similar in shape to Allosaurus, bipedal and with a long snout, and with fairly short arms. However, Concavenator becomes a true weirdo almost immediately upon seeing it - it has a hump on its back! No one really knows what this hump was used for - display? Thermoregulation? The mystery remains with us. However, that being said, it probably was at least a little distinctively colored, since it would have been a very noticeable feature on the back of Concavenator. The other interesting thing about this dinosaur? It probably had feathers. This is not necessarily a big deal in and of itself, except for the fact that Concavenator was a Carnosaur - a group of not-very-birdie dinosaurs. In fact, before animals like Kulindadromeus and Tianyulong were (mostly) confirmed to have feathers, it was right outside the group thought to have them - the Coelurosaurs. Concavenator has direct evidence of quill knobs on its arms; this evidence has been disputed, but significant unpublished research indicates that those are indeed what the structures are (so, grain of salt, and all that, until that research is published). 

By Slate Weasel, in the Public Domain 

Quill knobs usually mean pennaceous feathers, in the form of a wing-like structure, off of the arm. However, there is no direct evidence that pennaceous feathers evolved before animals like Gallimimus, which Concavenator is a few million years behind on; it would be a major leap in terms of determining when complicated feathers first evolved. So, while it’s possible that Concavenator had full wings, it may have also just had long, strand-like or ribbon-like feathers off of its arms, used for display - and precursors to the wings that would be found on its later-derived relatives. This has strong evidence, since the bumps were weirdly spaced and placed for quill knobs, indicating they weren’t quite at the structure found in properly winged dinosaurs. It is likely that at least some portion of its body was covered in simple feathers as well, since Concavenator was smaller than Yutyrannus - at 6 meters long. 

By Mario Lanzas, CC BY-SA 4.0 

Diet: Concavenator would have been a carnivore, feeding on small to medium sized animals in its environment. 

By Emily Willoughby, CC By 3.0 

Behavior: Given the presence of not one but two display structures (probably) on Concavenator, evidence suggests it was a social animal, using these structures to display and communicate with other members of the species. While probably endothermic, if it did use the hump for thermoregulation, it probably would have aided in keeping Concavenator cool in the hot early Cretaceous air. As such, it may have basked in its environment in the shade, letting blood flow through the hump and get cooled down (or warmed up) by the air. Concavenator may or may not have been a pack hunter - even out of convenience - in order to take down larger prey than it could alone. The wing feathers would have been able to be flipped out or drawn in to communicate with other Concavenator. As for its young, it is more likely than not that Concavenator cared for them, though the extent of this behavior is not known. 

By Antonin Jury, CC BY-SA 4.0 

Ecosystem: Concavenator lived in an extensive lake ecosystem, filled with deep subtropical lakes and wetlands with huge, swamp-filled plains. This was an extremely wet land, with a wide variety of green algae, aquatic flowering plants, conifers, cycads, and potentially cypress trees. Interestingly enough, the most common amniotes in this ecosystem were crocodilians - not dinosaurs or mammals! There were also a lot of amphibians, including Hylaebatrachus and Gracilibatrachus (a frog and a salamander), many many turtles such as Hoyasemys, plenty of lizards including Meyasaurus and Hoyalacerta, and mammals - including Spinolestes, which preserved soft tissue. Crocodyliformes included Cassissuchus, Montsecosuchus, and indeterminate members. As for pterosaurs, there was the fantastically crested Europejara. There were dinosaurs besides Concavenator, too - at least a few kinds of Troodontids such as Euronychodon and Paronychodon, the raptor Richardoestesia, the Ornithomimid Pelecanimimus, the ornithopod Mantellisaurus, and a variety of opposite birds! Opposite birds included some of the best known and earliest members of the group outside of China, such as Concornis, Eoalulavis, and Iberomesornis. As a large predator, Concavenator probably mainly fed on animals like Mantellisaurus, Pelecanimimus, and other larger creatures in the swamps. 

By José Carlos Cortés 

Other: Did Concavenator have these famous feathers? The debate has been an extensive one. Evidence has come out in many forms against and for it. While it seems ridiculous to suggest that the complex feathers usually attached to quill knobs evolved as early as the group of dinosaurs Concavenator is a part of, it isn’t actually that far-fetched - especially since it’s probable that Ornithomimosaurs, which are only a few steps removed from Concavenator, may have had them. However, it is still a major jump in the fossil evidence - and why wouldn’t we have fossils of animals in-between with such feathers? So the jury is out, but Concavenator does seem to have at least some evidence of complex feather structures on its arms - which points to the hypothesis that feathers first evolved at the base of the group including pterosaurs and dinosaurs, rather than just in the birdiest of the dinosaurs. Which not only means that any dinosaur of a reasonable size or a cold enough climate may have retained fluff, but that fancy display structures - like weird wing-like things - could have been found on so many dinosaurs, even giant ones. It is also possible that this indicates wing-like structures evolved multiple times in dinosaurs - or that dinosaurs tried out multiple types of wing-esque things before settling on the structures we see today. The possibilities are endless, and more research of Concavenator is needed to confirm them!

~ By Meig Dickson

Sources under the Cut

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Yamamato Takato