Lion/Bear Sized Dinosaurs

[Supercommunist]

It was surprisingly difficult for me to recall species of dinosaurs that are roughly the size of a modern apex predator, and a lot of the dinosaurs were actually sub adults. On most dinosaur size comparison charts, you'll have the itty bit dinosaurs, a couple of dog sized dinosaurs then suddenly jump the 1,000 pound plus animals. Since this is a forum that was once partially dedicated tpo AVA discussion, I figured it would be worth listing and discussing the dinosaurs a modern apex predator had a chance of beating.

Here is a list of theropods I could think of:

Xuanhanosaurus = 265 kg, 4.8 meters long, 1.3 meter hip height

Austroraptor = 340 kg, 6.2 meter long, 1.5 meter hip height

Troodon formosus = 380 kg, 5.4 meters longheight, 1.65 meter hip height

Frenguellisaurus/Herrerasaurus = 360 kg, 5.3 meters long, 1.55 meter hip height

Concavenator = 400 kg, 5.2 meters long, 1.9 meter hip height

Source: Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes

www.amazon.com/Dinosaur-Facts-Figures-Theropods-Dinosauriformes/dp/0691180318/ref=sr_1_1?crid=3W4LV4H3W3U4J&keywords=theropods&qid=1705298913&s=books&sprefix=theropod%2Cstripbooks%2C82&sr=1-1

The book also lists a decent amount of "large polar bear" tier predators like cryolophosaurus, but honestly it's kind of crazy how few "tiger tier" or "jaguar tier theropods" have been found.

According to a quick google search, Marshosaurus was about 400 to 500 pounds.

I also avoiding listing low hanging fruit like utahraptor, partly because it's so well known and partly because I am not sure which mass estimate is actually reliable.

[Infinity Blade]

I originally thought you could argue for Ceratosaurus being here, but after seeing this, it's clear you're going to need the largest extinct bears to contend with it (source->).


I also thought about Dilophosaurus. It's been estimated at >400 kg (430 kg according to one study I found, although I admittedly don't know how massive it would be based on this reconstruction by Randomdinos). You might need some of the larger extant bears to contend with it, but if it's "only" that massive it would qualify.


Gasosaurus (150 kg) might be of interest as well, although I admit it's a bit on the smaller side.

[Infinity Blade]

We might also be able to add Dubreuillosaurus (250 kg), Piatnitzkysaurus (275 kg), and Condorraptor (200 kg) to the list. All these estimates come from GSP's Princeton Field Guide.

[Supercommunist]

Gasosaurus (150 kg) might be of interest as well, although I admit it's a bit on the smaller side.

Part of the problem with this topic is the huge range of weight estimates. Just look at Gasosaurus' wikipedia page.

Gasosaurus is a carnivorous theropod with strong legs but short arms. It measured between 3.5 to 4 metres (11 to 13 ft) in length, with a weight of around 150 kilograms (330 lb). However, some estimates put its weight as high as 400 kilograms (880 lb),[2] as very little is known about it.

According to posts I've seen on the internet, Achillobator would have been 250 to 300 kg, while utahraptor would have been 500 kg? Are these estimates accurate?

[Infinity Blade]

Jan 16, 2024 10:20:55 GMT 5 Supercommunist said:

Gasosaurus (150 kg) might be of interest as well, although I admit it's a bit on the smaller side.

Part of the problem with this topic is the huge range of weight estimates. Just look at Gasosaurus' wikipedia page.

Gasosaurus is a carnivorous theropod with strong legs but short arms. It measured between 3.5 to 4 metres (11 to 13 ft) in length, with a weight of around 150 kilograms (330 lb). However, some estimates put its weight as high as 400 kilograms (880 lb),[2] as very little is known about it.

According to posts I've seen on the internet, Achillobator would have been 250 to 300 kg, while utahraptor would have been 500 kg? Are these estimates accurate?

For Utahraptor I've seen weight estimates vary from 250-300 kg to 470 kg. The former seems to be based on a museum mount. The latter is based on GDI by Internet-goers, using Scott Hartman's Utahraptor skeletal and a top view based on Greg Paul's Dromaeosaurus. On the one hand, I can see potential pitfalls in using another genus for a GDI (simply that, well, Dromaeosaurus is not Utahraptor). On the other hand, all museum mounts have something wrong with them (something Scott Hartman will tell you), so I'm really 100% sure which is really more correct. For what it's worth, the Princeton Field Guide puts Achillobator and Utahraptor at 250 kg and 300 kg, respectively.

Actually, I'm not really sure I can find a reliable source for Gasosaurus' weight anymore. This is the source Wikipedia cites for it being up to 400 kg, for one.

web.archive.org/web/20050307120910/http://palaeo.gly.bris.ac.uk/Dinos/Genlist/GenG/Gasostxg.html

[Supercommunist]

According to a quick google search sinosaurus was around 600 pounds. Based on the size charts I've seen that estimate seems reasonable.

[Supercommunist]

Xionguanlong. Weight estimates vary from 440 to 600 pounds.




There are some online sources that state Liliensternus weighed aroud 400 pounds.


x.com/TheAmazingSpino/status/1802214395868537240/photo/1

[Infinity Blade]

I feel like any juvenile of a giant tyrannosaurid species would technically count. I totally get that in one sense it's not fair in that they're by no stretch of the imagination the most formidable representatives of their species (not until they grow up anyway). But a juvenile T. rex would be on par with many adult carnivorans in body mass, is very cursorial, is still armed with a mouthful of ziphodont teeth and long kicking legs, and all around accomplished predators in their own right. They'd even be at an age where many extant predatory carnivorans would be well into their adulthood.

Chart by Franoys.


For example, CMNH 7541 was ~390 kg and ~8 years old at the time of death. Jane was ~660 kg and ~11 years old at the time of death.

[razor45dino]

how would these creatures do if they were appeared in an environment today

[Supercommunist]

Do we have any photos comparing 200 to 300 kg tyrannosaurus to modern carnivorans?