Defenses of dinosaurs without obvious weapons

[Infinity Blade]

^Amen to that.

I also believe that ornithopods or ceratopsians with quills could have also used them as deterrences to gain a head start to run away or attack.

[theropod]

Porcupine-like spikes are absolutely feasible. I can even see them as quite common, since they body shape and integument of many small ornitischians would probably be ideal prerequisites.

[Infinity Blade]

There were also speculations that pachycephalosaurs might have had rhino-like keratinous horns or the likes on their heads in life, the dome merely being a base.

Just look at my signature.

[theropod]

It looks cool, but doesn’t convince me. The thickness of the structure fits, but if that was the case I’d expect it to be rugose. On the other hand, pachycephalosaur domes are usually very smooth.

Also, at earlier ontogenetic stages they often already had horns with a bony core that were lost later.

[Infinity Blade]

deinonychusempire.deviantart.com/art/All-Your-Yesterdays-Contest-Crown-of-Thorns-348473346
^According to that guy, Sharpey's fibers (microscopic structures where keratin or flesh be anchored) were found on pachycephalosaur domes.

paleobiol.geoscienceworld.org/content/30/2/253.abstract
^That is the study which he mentions.

[theropod]

Thanks, I wasn’t aware of that!
That doesn’t necessarily mean there was a horn, but it’s actually a compelling hypothesis!

[Infinity Blade]

True.

[Deleted]

The presence of a protective keratin "helmet" is far more likely than a horn imo.

[mechafire]

Depends. Most duckbills have big heavy tails. Alot of dinosaurs can kick with their front or back legs. What's to stop them from biting?

[Infinity Blade]

student.societyforscience.org/article/dinos-some-were-‘marathoners’

Edit: this (hyperlink) too.

I quite recently found the above. Apparently, hadrosaurs had endurance on their side and were better long-term runners than potential predators (namely things like tyrannosaurs).

[creature386]

^Nice, looks like the common depiction of hadrosaurs as good runners is well founded.

[Infinity Blade]

To add to this, at least Hypacrosaurus could also outgrow predators. I think this could have easily applied to other hadrosaurs too.

phenomena.nationalgeographic.com/2008/08/06/duck-billed-dinosaur-defended-itself-by-outgrowing-predators/

[Supercommunist]

One question pertaining to that article. It states that it took thirty six years for a tyrannosaurus to reach adulthood. Last I recall, it was believed that a tyrannosaurus lived a maximum of thirty years. Has their been recent evidence suggesting that tyrannosaurus lived longer than thought, or was that a typo or something?

[Deleted]

The article writer was likely just misinformed regarding that part.

Tyrannosaurus were sexually mature by ~16-18 years and skeletally mature by something around ~25ish years.

Maximum lifespan is unknown, just like in basically every extinct prehistoric animal.

[creature386]

^Actually, the author just took the estimates from the cited paper:
rspb.royalsocietypublishing.org/content/275/1651/2609
I am not expert when it comes to growth modeling, so I can't tell if the estimates are correct or not. And to be honest, I hardly understand the paper. They say that 95% of the maximum femoral circumference is reached at 36 years, but their figure 3 does not go beyond 30 years. Moreover, they are aware of Horner & Padian's paper (2004) and even used data from it, yet got radically different growth results. I wonder if 36 years was a typo and they actually meant 26 years or something like that.

P.S. Sorry for getting off topic.