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Description
A carcharodontosaurid Concavenator corcovatus with hypothetical filamentous integument.

Described in 2010, Concavenator is known from an almost complete and very well preserved skeleton with some soft tissue impressions. This theropod of rather modest (5.8 m) size compared to its more derived relatives had two ridges along the ridge, the first of which was located in front of the pelvis and had the shape of a shark fin. Most likely, they served for demonstration.

One feature of the anatomy of the Concavenator caused a lot of controversy among paleontologists. These are the so-called "quill knobs" located on the surface of the ulna. Similar structures are known to be known in several maniraptorans and are considered sites of attachment of large flight feathers. However, Concavenator was an allosauroid, not a coelurosaur, and certainly not a maniraptor, so the presence of this trait aroused the strong curiosity of scientists. The team of researchers who described the taxon suggested that hollow filaments were attached to the "quill knobs" of Concavenator. This would confirm the emergence of protofeathers already in Carnosauria. Paleontologists such as Darren Naish and Andrea Cau disagreed with this conclusion. In their opinion, a number of tubercles are located not on the back side of the bone, but on the anterolateral one, unlike the real quill knobs of maniraptorans. This would mean that the described structures are actually an intermuscular ridge. Elena Cuesta Fidalgo, who described the skeleton, objected in 2018 that some birds (for example, reed warblers) have similarly positioned quill knobs and that the reconstruction of the musculature contradicts the interpretation of the "intermuscular ridge". In other words, the first version may still be relevant. Whether this is really the case - future findings will show. In any case, the presence of real flight feathers in Concavenator is a strange and unlikely outcome.

In this drawing, Concavenator is shown with a partial cover of protofeathers, but without large feathers or "quills" on the "hands". So I decided to depict an allosauroid with feathers and at the same time emphasize the controversial interpretation of the "quill knobss". The remaining integuments were restored on the basis of skin impressions from the object of the drawing (scutes on the feet and the lower part of the tail) and Allosaurus jimmadseni (scale impressions from three specimens, including snake-likescutes on the throat, unfortunately not illustrated in the papers). The result is generally satisfactory, although there were difficulties with drawing the claw of the thumb of the right hand.

Black gel ink and black ballpoint pens and black colored pencil, 2022.

Description
A carcharodontosaurid Concavenator corcovatus with hypothetical filamentous integument.

Described in 2010, Concavenator is known from an almost complete and very well preserved skeleton with some soft tissue impressions. This theropod of rather modest (5.8 m) size compared to its more derived relatives had two ridges along the ridge, the first of which was located in front of the pelvis and had the shape of a shark fin. Most likely, they served for demonstration.

One feature of the anatomy of the Concavenator caused a lot of controversy among paleontologists. These are the so-called "quill knobs" located on the surface of the ulna. Similar structures are known to be known in several maniraptorans and are considered sites of attachment of large flight feathers. However, Concavenator was an allosauroid, not a coelurosaur, and certainly not a maniraptor, so the presence of this trait aroused the strong curiosity of scientists. The team of researchers who described the taxon suggested that hollow filaments were attached to the "quill knobs" of Concavenator. This would confirm the emergence of protofeathers already in Carnosauria. Paleontologists such as Darren Naish and Andrea Cau disagreed with this conclusion. In their opinion, a number of tubercles are located not on the back side of the bone, but on the anterolateral one, unlike the real quill knobs of maniraptorans. This would mean that the described structures are actually an intermuscular ridge. Elena Cuesta Fidalgo, who described the skeleton, objected in 2018 that some birds (for example, reed warblers) have similarly positioned quill knobs and that the reconstruction of the musculature contradicts the interpretation of the "intermuscular ridge". In other words, the first version may still be relevant. Whether this is really the case - future findings will show. In any case, the presence of real flight feathers in Concavenator is a strange and unlikely outcome.

In this drawing, Concavenator is shown with a partial cover of protofeathers, but without large feathers or "quills" on the "hands". So I decided to depict an allosauroid with feathers and at the same time emphasize the controversial interpretation of the "quill knobss". The remaining integuments were restored on the basis of skin impressions from the object of the drawing (scutes on the feet and the lower part of the tail) and Allosaurus jimmadseni (scale impressions from three specimens, including snake-likescutes on the throat, unfortunately not illustrated in the papers). The result is generally satisfactory, although there were difficulties with drawing the claw of the thumb of the right hand.

Black gel ink and black ballpoint pens and black colored pencil, 2022.