Why T rex had Short Arms

[Tidgy's Dad]

Not really a lot of answers. 

From BBC News : 

https://www.bbc.com/news/science-environment-62088874

[Crusty_Crab]

From the paper, this seems to be the crux of their argument: "Historically, there has been great interest in inferring the potential functions of the proportionately diminutive limbs in large theropods like T. rex, with interpretations including reproductive behavior,1 body support when an animal is rising from a prone position,30,31 or predatory behavior.32,33 Other authors have considered the forelimbs of tyrannosaurids and abelisaurids as vestigial with limited or no function,34,  35,  36 whereas a third school of thought has been to distinguish the question of function in individual species from macroevolutionary processes that may account for arm reduction in these species perhaps as a result of selection for other traits.37,  38,  39 Our study provides some support for the latter hypothesis with similar proportions observed in unrelated large predatory theropod lineages. The presence of multi-ton theropods with long forelimbs, but small skulls, such as the ornithomimosaur Deinocheirus and the caenagnathid Gigantoraptor, further confirms that forelimb reduction is not a simple function of body size in theropods, but rather that it tracks some other trait, which for large predatory species is likely skull size."

 

My translation, there are 3 explanations why T-Rex had short forelimbs:

1. They had a function, such as rising from lying down

2. They were useless

3. Small forelimbs may be linked with another trait. Evolution may favor that other trait, inversely proportional to the trait of forelimb size.

 

The authors favor the third hypothesis. They suggest skull size as the linked trait. Therefore, evolution may favor a bigger skull size, which is linked to smaller forelimbs. The bigger the skulls, the more fit the animal is, and thus the smaller the forelimbs, 

[Tidgy's Dad]

2 hours ago, Crusty_Crab said:

 

My translation, there are 3 explanations why T-Rex had short forelimbs:

1. They had a function, such as rising from lying down

2. They were useless

3. Small forelimbs may be linked with another trait. Evolution may favor that other trait, inversely proportional to the trait of forelimb size.

 

They also mention at one point that the little arms might be used for grasping the female during mating. 

[Crusty_Crab]

19 minutes ago, Tidgy's Dad said:

They also mention at one point that the little arms might be used for grasping the female during mating. 

I noticed that too. That was cited in the BBC article but not in their paper. Seems like a discrepancy which I can only explain that science reporters for mass market outlets may either 1. not understand the science or 2. may not take the time to adequately understand the science due to deadline constraints. 

[Tidgy's Dad]

1 hour ago, Crusty_Crab said:

I noticed that too. That was cited in the BBC article but not in their paper. Seems like a discrepancy which I can only explain that science reporters for mass market outlets may either 1. not understand the science or 2. may not take the time to adequately understand the science due to deadline constraints. 

or that a scientist mentions their opinion which is not in the paper to a journalist. 

[Crusty_Crab]

5 minutes ago, Tidgy's Dad said:

or that a scientist mentions their opinion which is not in the paper to a journalist. 

Absolutely true as well. Science reporting seems to be formulaic:

1. Summarize the findings

2. Get a quote from the authors about why it is significant

3. Get a quote from an independent scientist (someone that was not involved in the paper)

 

Typically though, they would cite everyone they interviewed. Therefore, if someone made a conclusion that was not in the paper, they would usually attribute that person. But then again, I'm not in the journalism business so I can't really say what meets with current journalistic practice.

Edited July 8, 2022 by Crusty_Crab