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DrScottHartman — Ornitholestes
Published: 2007-02-14 22:24:10 +0000 UTC; Views: 18187; Favourites: 242; Downloads: 680
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Description
This is the classic small theropod from North America, but it turns out that Ornitholestes has been harder to pin down than researchers originally thought. It appears to be more closely related to birds than the allosaur-grade theropod that some thought. While it's not as close to Paraves as say oviraptosaurs, there are a couple features that seem to be "proto-deinonychosaur" in general, including the narrowing and somewhat stiffened distal tail, and a sort of incipient "killer claw" on the second toe. I wish more was known of the wrist and pectoral girdle, but for now they are speculations based on where Ornitholestes comes out in phylogenetic studies. Even at this stage of bird evolution Ornitholestes was almost certainly covered in a fur-like feather covering, and quite possibly sported proto-wings on its hands and tail.Edit 2016: I was treated to some high resolution images, some from angles not previously available in print. It turns out that the pelvis did not have a vertical pubis, and the hind legs were more robust than my earlier skeletal.
I posted this right away (I don't want new art to be done without it), but my Patreon supporters www.patreon.com/skeletaldrawin… a behind the scenes look that showed what has changed between the original version in 2007, the 2013 revision, and the current update.
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Comments: 70
Depending on the phylogenetic analysis, yes.
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Alright, then. I guess it's nice to see that "Jurassic raptors" really did exist.
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Well, I didn't mean actual deinonychosaurs, just their closest relatives.
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The way I see it, maybe they should have utilized Marshosaurus to stand in for the Velociraptors rather than just beef up old Velo to the size of a Deinonychus.
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Raptors don't exist until the Cenozoic. Or did you mean deinonychosaurs?
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I actually meant deinonychosaurs and their closest relatives, not the birds of prey.
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I knew that's what you meant, but it's really preferable to use the proper terms, rather than one that is more correctly used for another group of dinosaurs.
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Would coelurosaurians be okay?
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Thank you for your beautiful skeletals! Just finished a quick sketch of Ornitholestes hermanni based on your skeletal reconstruction (feather pattern from the theory that it may fit into the Microraptor clade). It's here , if you're interested in checking it out!
I look forward to being continuously inspired by your work!
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Looking between Ornitholestes and Jiangchangosaurus (and other basal therizinosaurs) they seem to have quite a few similarities; maybe Ornitholestes is a very basal therizinosaur?
Probably not, but it's interesting to hypothesize, nonetheless.
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Maybe or not;in many Tree Ornitholestes was on the backbone of Maniraptoriformes and far fron Therizino.We still don't know what has happend between the backbone Miniraptoriformes and Fukuivenator-specialized carpel and finger,maybe mean that there is a climbing animal.(My English was pool and maybe made a lot of mistakes,I'm sorry about it.)
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I miss its "horn", but I like how now is a "proto-deinonychosaur"
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My only memories of Ornitholestes as a kid are that it was the dinosaur always chasing Archaeopteryx in paintings.
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"My only memories of Ornitholestes as a kid are that it was the dinosaur always chasing Archaeopteryx in paintings"
I remember this cliche'. In my young mind Ornitholestes was the jurassic equivalent of Willy E. Coyote (and given its ecological niche that was not so far from true).
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"Walking With Dinosaurs" introduced me to Ornitholestes. Good show, but has some flaws.
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Anatomically it has a _lot_ of flaws, but it was still one of the first to at least try and treat dinosaurs like real animals.
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Ah yes, good point.
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Gee this thing is kind of weirdly convergent on nosasaurids.
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You're right. That's sort of odd, but very cool.
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I knew that Ornitholestes was a small Morrison tyrannosaur, but unlike tyrannosaurs, Ornitholestes was a closer base of the paraves. Great one!
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Definitely different from the animal depicted in Walking with Dinosaurs . I knew that the nasal horn had been discredited, but I hadn't realized that it had a proto-sickle claw akin to the raptors and troodons.
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The Tyrrell's Ornitholestes casts are actually mounted with hyperextended second toes. With Dromaeosaurus mounted in the gallery nearby, the resemblance is striking.
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I can imagine. I found some photos of that mount - I like it!
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Want to know a vaguely creepy coincidence? The updated image file I uploaded was titled Ornitholestes[1].jpg.
Cue the Twilight Zone music
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Doo de doo doo doo dee doo doo...There is a fifth dimension, beyond that which is known to....Eh, never mind.
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I didn't know it has such a confirmed "raptor claw", that is indeed quite intriguing. Is it lifted to the maximum in this restoration? As in - lift it any more, and it will break or cause pain? If the claw has grown this much by this species, it is sign that it has been an adapted feature for quite some time. How sure are we still about Archaeopteryx lifted toe? Archie's claw isn't even that much bigger than the other, which makes me curious wether the claw grows large first, or the toe flexibility, evolutionary speaking.
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I'm really sure about Archaeopteryx, seeing as how I've personally spent hours examining the specimen in question (the Thermopolis Specimen). I'm only working from photographs and measurements on Ornitholestes, so I'm not as sure about the range of motion, but I suspect it can extend at least a bit more (though perhaps not to where it would be comfortable to carry around).
It's always possible that Archaeopteryx had secondarily reduced the size of the claw. Or perhaps whatever initial function they had (e.g. prey acquisition) soon led to a wide range of morphs as the toe was adapted to different lifestyles. As I think I mentioned in response to someone else, even some oviraptorids seem to show evidence of the toe proportions (shortened digit 2 with subequal 3 & 4), despite lacking the ability to hyperextend the second toe (and not having a scythe claw).
Another thing people may not be giving enough consideration to is how often theropods manipulated objects with their feet. As the hands became more incorporated into the wing (or reduced in some large theropods) pedal manipulation may have become more common...it certainly works for living theropods.
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I know is comment is >3 years old, but regarding the foot manipulation part, does this include even theropods that lacked an opposable hallux (seems to be implied by your mention of large theropods with reduced hands)? Could their halluces still facilitate gripping even if not opposable?
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Indeed, I had not thought much about foot-manipulation - then again, I feel most people have ignored theropod hands in general, leaving them hanging there like useless appendages, while evidence suggest otherwise - such as simply: Large hands. Even comparatively small hands, such as carnosaurid hands are still large, and clearly had to be used for something. In yet another un-scanned drawing of a megalosaurid, I wanted to add a subtle attention to that, by showing it curling its fingers inwards - instead of just leaving them hanging - so to suggest that it is moving and curling and stretching its fingers while walking, kindov like a bored person tapping fingers against the desk
Lately I've also begun to imagine Tyrannosaurus mini-hands (which are remarkably well developed despite size) to be for communicative flapping 
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It is an ancestor of the dromeosaurs and a member of the Maniraptora clade, but not a raptor in and of itself.
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Thank you for the information.
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No, it's not a dromaeosaur, but it may hint that it's closer to the base of paraves than previously thought. Alternatively, the hyper-extended second toe might be distributed more widely than we thought.
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I read somewhere that this little guy might have been a very primitive tyrannosauroid. Any truth to that?
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It's true that someone proposed it 
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It's not just you.
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Definitely not. The idea stemmed from a displaced nasal, but further preparation of the specimen has shown that there was no nose horn on Ornitholestes.
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