Feranec, 2004, Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of Smilodon fatalis from Rancho La Brea: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 206, p. 303-310.
What’s it about?
Sabertoothed mammals are so named because of their massive, elongate canines. A natural question to ask is, how does it get so long? The major ideas are that the teeth grow for a very long time (which would affect how the animals survived before the teeth were fully grown), that they grew very quickly, or some combination.
The author uses isotopes of oxygen from the tooth enamel of some adult sabertooth tigers (Smilodon fatalis) to estimate how long it tooth the tooth to grow. This he compares with known growth rates and timing of development of modern lions and tigers to see how it compares.
Why does it matter?
He found that the saber teeth (canines) of Smilodon grow about 7 mm per month and take 18 months to grow. Lion canines grow about 1.3-3.3 mm per month for 17-27 months. Tiger canines are longer than those of lions, but finish growing much earlier. Average growth rates in tigers is about 8.5-21.2 mm per month. What this shows is that the hypothesis of mixing changing growth rates and durations of growth both play a role in making the canines of Smilodon so long.
Why did I read this?
Apparently, I read this paper ages ago, judging by how my name appears in the acknowledgements. But it’s isotopes and the author is a personal friend, so there you are! I’ve also been thinking a lot about canines lately, so this paper naturally popped up as something I needed to read.