Pack hunting theropods

[Infinity Blade]

The title explains everything; this thread is about the notion of pack hunting in extinct theropod dinosaurs and the nature thereof (i.e. mammalian-style cooperative hunting, communal hunting). Post your opinions regarding the topic.

[Infinity Blade]

It doesn't look like this thread will get attention if I don't bump it up, so I'm going to be the first to contribute.

The way I see it...

Theropods did, in fact, have the mental capacity to develop cooperative hunting (of the mammalian and avian type) if certain ecological pressures forced them to do so. We know this because Harris' hawk (Parabuteo unicinctus) is an extant theropod that practices cooperative hunting. Even if more bird-like theropods were more intelligent than others, I doubt the latter would have been any less intelligent than modern crocodilians, which themselves practice already rather sophisticated group hunting techniques (reference). So even if some theropods weren't as intelligent as those closer to birds, I doubt they would need to take huge leaps to develop cooperative pack hunting behavior if pressed.

Heck, there are theropods alive today that are even smarter than these birds of prey (i.e. corvids and parrots, which are thought to rival primates in intelligence IIRC; you don't need to be that smart to be a cooperative pack hunter). And there are more bird species that are this intelligent than there are cooperative pack hunters (as, correct me if I'm wrong, Harris' hawk is the only bird that practices this behavior). That alone suggests to me that it's not so much a matter of "were theropods intelligent enough?" as it is one of "were there any ecological pressures that would have driven theropods to develop advanced cooperative hunting behavior?". In other words, "did any of them need it?". Given how non-avian theropods existed for ~165 million years, I'd be shocked if no taxon was ever ecologically pressed to become pack hunters akin to today's Harris' hawk and some carnivorans.

Correct me wherever I'm wrong.

[creature386]

There are some people who think that Deinonychus only mobbed Tenontosaurus in groups instead of engaging in coordinated pack hunting:
www.bioone.org/doi/abs/10.3374/0079-032X%282007%2948%5B103%3AAROCPH%5D2.0.CO%3B2
(I have only read the abstract, but I wonder if these "diapsids" include birds as well)
That being said, I agree with Ausar. I can imagine that there were theropods who hunted in packs and others who didn't, but telling who was who is of course going to be difficult.

[dinosauria101]

Well we do have fossil evidence for Gorgosaurus and Daspletosaurus, as well as Megaraptor, Deinonychus, Aucasaurus, and Mapusaurus. I think it's safe to say those species engaged from time to time at the least.

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A list of literature regarding cooperative hunting in today's predatory theropods.

Group Hunting by Harris’ Hawks in Texas-> (Coulson & Coulson, 1995)

Social Foraging Classes in Raptorial Birds-> (Ellis et al., 1993)

Cooperative Hunting in Harris' Hawks (Parabuteo unicinctus)-> (Bednarz, 1988)

Reexamining Cooperative Hunting in Harris's Hawk (Parabuteo unicinctus): Large Prey or Challenging Habitats?-> (Coulson & Coulson, 2013)

[Infinity Blade]

The paper right below discusses a bone bed of Albertosaurus discovered by Barnum Brown in 1910. It provides possible evidence of gregarious behavior in this species.

Possible Evidence of Gregarious Behavior in Tyrannosaurids-> (Currie, 1998)

Below is a later paper on the same subject, also suggesting that gregariousness was likely (interestingly, it also mentions some evidence suggesting Daspletosaurus sp. may have been gregarious).

On gregarious behavior in Albertosaurus-> (Currie & Eberth, 2010)

[all]

I agree  theropods at least some of them did have intelligence  to be pack hunters. As it was mentioned crocodiles can cooperate well together and are smart predators. Theropods are often described as having large eyes and large brains. I don't know exact dimensions but there is an interesting fact brain of birds although small generally have high neuron density, even though it is visible more in one specie than other. However brain of raven for example is four times as dense as brains of primates. and since birds are  descendants of theropods even though brains of theropod brains were probably not as neuron dense as those of corvids or even many of the other bird species. There is a possibility that they were denser than those of other herbivore dinosaurs or modern crocodiles.   

[Infinity Blade]

So apparently back in 2016 there was an abstract that reported potential trackway evidence upon a ceratopsian by theropods in the Moreno Hill Formation.

TRACKWAY EVIDENCE FOR A THEROPOD GROUP ATTACK UPON A POSSIBLE CERATOPSIAN DINOSAUR FROM THE MORENO HILL FORMATION (TURONIAN) NEW MEXICO
WOLFE, Douglas G., White Mountain Dinosaur Exploration Center, Greer, AZ, United States of America; WOLFE, Hazel D., White Mountain Dinosaur Exploration Center, Greer, AZ, United States of America

Track impressions upon a fallen sandstone block reveal multiple three-toed (theropod) dinosaur tracks; associated with a large, shallowly-impressed, circular track exhibiting the pedal architecture of a quadrupedal, possibly ceratopsian, ornithischian. The track site lies near, and stratigraphically slightly above, the Moreno Hill Formation (Turonian) dinosaur type localities (the Zuni Fauna), including Zuniceratops, Nothronychus, Jeyawati and a new theropod dinosaur currently under study. The track surface is a silty-muddy interval atop the lower of two prominent and widely persistent channel sandstones; the track surface now lies perpendicular to horizontal. The theropod tracks are “muddy”; deeply impressed into a water-rich substrate which slumped into the impressions, while also preserving features such as claw impressions. Mapping the three-toed tracks reveals at least three sizes (up to 33.5 cm wide) of tridactyl tracks (including a matched stride-pair) exhibiting a wide inter-digit angle and morphology comparable with theropods such as tyrannosauroids. Several of the theropod tracks are oriented toward, and then away from, the posterior margin of the circular track. The ungual impressions of the circular (approximately 34 cm) track suggest rapid movement away from the oncoming three-toed tracks. The circular track is less impressed into the substrate than the three-toed tracks, apparently more buoyant on the muddy substrate. The assemblage of tracks appears a rare example of positive evidence for a cooperative and active pursuit by a group of theropod predators, (possibly tyrannosauroid), upon an equally large four-legged (possibly ceratopsian) dinosaur. The sandstone surface nearby preserves swimming tail/track impressions interpreted as crocodilian, in-situ tree stumps are documented in nearby finer-grained facies, the Zuniceratops holotype coracoid contains D-shaped bite penetrations with surface checking of the elements suggesting inundation-desiccation, and the Zuniceratops bone bed was deposited within a “log-jam” channel deposit. Together these data demonstrate a close association between submerged and emergent environments with predator and prey elements interacting at the margins. Zuniceratops (or other quadrupedal ornithischian) probably sought shelter from more land-bound predators by risking danger within crocodile-inhabited wetlands, as do many modern terrestrial herbivores.

www.researchgate.net/profile/Daniela_Winkler2/publication/310263174_Functional_morphology_of_molars_in_ungulates_constraints_and_common_features/links/582ae1ae08aef19cb8061d74/Functional-morphology-of-molars-in-ungulates-constraints-and-common-features.pdf

Of course, the aforementioned theropod is now known as Suskityrannus. Obviously, this finding has been given due skepticism, although one of the authors interestingly pointed out that the animals would not all have left tracks if they hadn't crossed the mud patch at roughly the same time (link->).

[Infinity Blade]

I made a new post in the Teratophoneus profile with more potential evidence for gregariousness in tyrannosaurids.

theworldofanimals.proboards.com/post/60947

[Infinity Blade]

I found a really interesting paper that seeks to view social hunting in animals in a multidimensional manner (Lang & Farine, 2017). It looks at five different aspects to categorize the kind of social hunting a species exhibits. Maybe we should be examining social hunting in animals more like this.