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Aquaraptorids

By ZoPteryx
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Sketches of the various postures and movements of the aquaraptorids along with profiles of the five different genera.

The genus Aquaraptor (Finraptors) can be found around coastlines worldwide and is composed of about twelve different species.  They are generalists that feed primarily on small fish, squid, and krill.  Most species are highly social, forming large feeding flocks lead by a dominant pair, but these dissolve when not hunting.  The largest species stretch a little over 3 meters long, but most are in the 1.5-2 meter range.

Pinnipedosaurus (Snubsnouts) is composed of four large species (to 5 meters) found mainly in the southern hemisphere.  They are the most cold adapted of the group and large individual may even brave the Antarctic winter.  They feed mainly in very deep waters on fish, cephalopods, and crustaceans; they are thought to search for prey mainly along the bottom.  Males posses an erectable crest just behind their nostrils; the snouts of both genders are completely feathered.  Females and young tend to gather into small groups, males are antisocial.

The three species in the genus Carcharaptor (Blazes) are all 3 meter long macropredators of birds, large fish, and smaller relatives.  They can be found worldwide, but prefer to stick to the temperate and polar regions.  They have proportionally the longest forelimbs of the group and are capable of great bursts of speed, but are very clumsy on land.  They are antisocial outside the breeding season and should be treated with extreme caution.  Their common is derived from the "blaze marking" present on the neck in all species.

With over twenty species found worldwide, Anatoraptor (Duckies) is the most diverse genus; there is some debate over whether the genus should be split into two or even three genera.  With duck-like snouts and tiny teeth, these species feed on the bottom or dabble on the surface for small organisms.  They have long hindlimbs and relatively short primary feathers, rendering them slow swimmers.  They are unaggressive and often social.  The largest species can grow to 4 meters in length, while the smallest stretches just 0.5 meters.

The name Molluscavenator (Snaggles) seems to have narrowly edged out "Thalattosauromimus" in the race for priority.  This genus of six mid-sized (2-3 meter) species can be found primarily in the northern hemisphere.  As their name suggests, they prey mainly on shelled invertebrates using their peculiarly shaped snouts and blunt teeth, but they will also take small fish and squid.  They live in small groups that are very protective over their feeding grounds, but direct conflict is usually avoided thanks to the cranial crests possessed by both genders of all species.

*Generally accepted common names given in quotes
**Lengths are total lengths, not SVL
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Saurocene Intro

Aquaraptoriformes Intro

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Comments21
anonymous's avatar
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archeoraptor38's avatar
wow you predicted that semaiquatic dromedosaur
Multiomniversal124's avatar
Sheather888's avatar
Very adorable, great concepts!
ZoPteryx's avatar
Dontknowwhattodraw94's avatar
Penguin-dinosaurs are cool, it would be awesome if we would actually find such a fossil :D
ZoPteryx's avatar
Indeed it would!
Evenape's avatar
Would they have made more thrust with leg wings? :p
ZoPteryx's avatar
Perhaps, my only concern with that would be the recovery stroke.  Webbed feet can be closed, but unless the leg feathers were mobile, I think they'd be counterproductive.

Althouuuugh, if the hind limbs could be flapped like the forelimbs......now you've got me think about four-winged swimming birds! :D (Big Grin) 
Evenape's avatar
Indeed... But we can have groups of muscles controlling feathers, no?

How to flap them though... Feet were not designed for lateral movement.... Glad to make you some ideas though :)
indigomagpie's avatar
Also, could feathers be made rigid enough for large animals to swim with? I'm not entirely sure about the feathered wings - mightn't something more like a penguin wing, all bone and soft tissue with vestigial remiges, work better at those sizes?
Evenape's avatar
I think that any feathers would need aerodynamics more than rigidity... It needs to be slender etc... If you are really hard pressed to use feathers on them then check out gannets and other diving birds, but I think the penguin shape is much better./
indigomagpie's avatar
Yes, but gannets and cormorants etc. swim with their feet, with their wings folded. Gannet wings are optimised for flight with no pressures pushing them in any other direction.

Also gannets are a lot smaller than aquaraptorids.

Birds that swim with their wings: auks, diving-petrels, penguins, and I'm pretty sure that's all. Now, diving-petrels and auks (other than great auks) have a narrow arm with long primaries, but that's because they fly. Auk wings are an evolutionary compromise between being ideal for swimming (where you need something small, sturdy and solid) and ideal for flight (where you need something large and thin and it doesn't have to be quite as stiff).

That compromise only works at small sizes. Diving-petrels are all tiny. The largest flying auk, the razorbill, weighs less than 1kg. With a bird much bigger than that, any wing small enough to swim well with is going to be too small for flight. That's why great auks lost their flight ability and evolved what looked like penguin wings. And that's why other auks have such disproportionately small wings relative to their body size, so that they can only fly very fast in straight lines.

Now, aquaraptorids are as aerodynamic as tuna, and I don't think they're even descended from flying ancestors. So there's no pressure at all for them to have long aerodynamic primaries. Like penguins or great auks, all the evolutionary pressures are focused on creating a wing that's good for swimming. So I'd expect them to have similar wings to penguins or great auks.

Of course, penguins evolved from some kind of generic neognath with normal modern-bird-looking wings - fused fingers etc - whereas aquaraptorids started out with unspecialised maniraptoran arms. So I suppose that could lead to them having free fingers connected by some kind of webbed membrane.

however, aquaraptorids are very specialised for aquatic life, and I notice that specialised aquatic mammals tend to remodel their arms into flippers that look like penguin wings. Whales used to have cloven hooves. Now they have flippers. Seals used to have nondescript mammalian paws with all the fingers free. Now they have fused flippers (otarids are particularly relevant here because they swim by flapping their arms like penguins). Mammals that swim with free-but-webbed fingers are things like otters, beavers, desmans, that spend a lot of time on land and need their feet to be a compromise between walking and swimming. The only fully aquatic mammal with normal-mammal-looking feet is the sea otter, and that's probably just because they evolved full aquaticity quite recently and haven't had time to develop flippers yet.

Also note sea turtles and plesiosaurs, which evolved from animals with free toes and, after extensive specialisation to a aquatic life, wound up with penguin-style or otarid-style flippers
Evenape's avatar
I agree with your conclusions... A paddle model should be what we're aiming for with this creature's forelimbs
OldDocHudsonandCO's avatar
So would these be the dinosaur equivalent of seals, otters, etc. ? If so, fascinating XD 
ZoPteryx's avatar
Exactly, and thank you!
OldDocHudsonandCO's avatar
DinoBirdMan's avatar
Nice work! And this is reminds me a penguin behavior.
ZoPteryx's avatar
Thank you!  Yeah, I tried to incorporate some penguin behavior. :) (Smile) 
DinoBirdMan's avatar
anonymous's avatar
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