Freak Felids - A Discussion of History's Largest Felines

[tigerluver]

Great year to have a new giant Machairodus. Here are the size takeaways:

Humerus length: 460.5 mm (longest felid humerus on record)
Mediolateral width of distal end: 123.3 mm
Anteroposterior diameter of midshaft: 46 mm
Distal articular width: 88.2 mm

The three mass estimates are as follows:

From the Christiansen and Harris (2005) articular width equation: 348 kg
- The scale factor in this equation is extremely negatively allometric (2.186). This probably is an underestimate, especially considering Machairodus had narrow bones.

The same source, but the humerus length equation: 405 kg
- One issue is the humerus length in Christiansen and Harris (2005) is articular. This gets missed often. In some animals this matters more than others. In this specimen, the greater tubercle is quite a bit higher than the head of the humerus, meaning the articular width would be significantly less. Using Peigne et al. (2005), the articular length is 95% of the total length in Machairodus. So the articular length is actually about 438 mm. Applying this to the same equation results in a mass of 351 kg.

The final estimation is actually from an Anyonge (1993) circumference formula: 427 kg

It's a bit confusing so I will first just quote it:
"The body mass estimate for M. lahayishupup based on humerus circumference is very similar to the one calculated based on humerus length. A diameter of 42.4 mm yields an estimate of 427 kg."

So they present a new diameter of 42.4 mm which they then either converted into the circumference of a circle or measured the circumference (not explicitly reported in the paper) and worked their way backwards. The circumference is 133.2 mm.

The Anyongle scale factor is 3. Anyonge equation have been called into question after Christiansen and Harris (2005) for overestimating but this is also species dependent. Reply