|
|
Post by elosha11 on May 12, 2023 15:59:14 GMT 5
Recently, a study came out that found a trend of decreasing body size through time in the European cave lion ( Panthera spelaea). One specimen of P. s. fossilis was estimated at over 500 kg. In truth, there were three different methods used to estimate body size in these lions. For the Sambir lion (the specimen in question), an estimate based on calcaneus length resulted in an estimate of 912 kg. This is obviously unprecedented in size for any felid, and the authors consider this to be relatively unreliable. However, they also feel that an estimate based on the length of the first molar is an underestimate (353.2 kg). A third method, multiplying m1 length by breadth, resulted in 440 kg. The authors do not specify how >500 kg was arrived at. In fact, in context, it appears to be an arbitrary, if educated, inference. Take it for what you will. References:Marciszak, A., Ivanoff, D.V., Semenov, Y.A. et al. The Quaternary lions of Ukraine and a trend of decreasing size in Panthera spelaea. J Mammal Evol (2022). doi.org/10.1007/s10914-022-09635-3I just saw this. Has there been any further criticism or commentary at the methodologies used? I just have to say -- holy sh*t. I knew cave lions were a very large feline, but I thought usually it was just a bit larger than modern-day tigers and lions. This would mean at some point in its life history it was potentially at the largest known the sizes of felids, at or even exceeding the size of Smilodon Populator. Even the lower size estimates for this particular Sambir individual are enormous. I wonder if it's possible this specimen was a statistical outlier, like a giant. It's not impossible for an atypical giant specimen to be preserved in the fossil record |
|
|
|
Post by Infinity Blade on May 12, 2023 20:28:41 GMT 5
Recently, a study came out that found a trend of decreasing body size through time in the European cave lion ( Panthera spelaea). One specimen of P. s. fossilis was estimated at over 500 kg. In truth, there were three different methods used to estimate body size in these lions. For the Sambir lion (the specimen in question), an estimate based on calcaneus length resulted in an estimate of 912 kg. This is obviously unprecedented in size for any felid, and the authors consider this to be relatively unreliable. However, they also feel that an estimate based on the length of the first molar is an underestimate (353.2 kg). A third method, multiplying m1 length by breadth, resulted in 440 kg. The authors do not specify how >500 kg was arrived at. In fact, in context, it appears to be an arbitrary, if educated, inference. Take it for what you will. References:Marciszak, A., Ivanoff, D.V., Semenov, Y.A. et al. The Quaternary lions of Ukraine and a trend of decreasing size in Panthera spelaea. J Mammal Evol (2022). doi.org/10.1007/s10914-022-09635-3I just saw this. Has there been any further criticism or commentary at the methodologies used? I just have to say -- holy sh*t. I knew cave lions were a very large feline, but I thought usually it was just a bit larger than modern-day tigers and lions. This would mean at some point in its life history it was potentially at the largest known the sizes of felids, at or even exceeding the size of Smilodon Populator. Even the lower size estimates for this particular Sambir individual are enormous. I wonder if it's possible this specimen was a statistical outlier, like a giant. It's not impossible for an atypical giant specimen to be preserved in the fossil record I haven’t seen any further word on it. Honestly, I wonder if at least part of that is because we’re at a loss for words for it. The mass estimate is huge, bigger than that of any other felid, but it’s also perhaps not an extreme departure from what we know about the largest felids (i.e. some of the largest species/individuals could weigh >400 kg). At least the way I look at it, I’m on the fence asking myself “is this really plausible?”. I could buy an exceptionally large extinct cat weighing 500 kg, but is that really what this cat is? The fact that I don’t know how this estimate was arrived at doesn’t help matters, though. |
|
|
|
Post by Infinity Blade on Jun 14, 2023 7:16:48 GMT 5
Anancus arvernensisA recent in vivo reconstruction of the straight-tusked gomphotheriid Anancus arvernensis had its body mass measured via the volumetric approach. The results suggest an animal weighing 5.2 to 6 tonnes ( Romano et al., 2023). 
|
|
|
|
Post by theropod on Aug 13, 2023 23:55:56 GMT 5
Maip macrothorax (holotype)
[m&m] I used Figure 1A of Aranciaga Rolando et al. (2022) as a guide to make a silhouette reconstruction (by straightening out the tail of the reconstruction), and Figure 1B to estimate the appropriate width/depth ratio of the thorax. I then ran a GDI on the silhouette reconstruction, assuming elliptical cross-sections. For simplicity, I applied the depth-width ratio observed in the thoracic section in Figure 1B, which is approx. 0.743, to the entire animal’s body, including the limbs. Scaling is based on the scalebar in the figure. The resulting silhouette ends up almost exactly 10 m long, which matches up well with previous length estimates.
Results and Discussion: Fig. 1: silhouette reconstruction showing lateral and dorsal view of axial segment, and lateral and anterior views of fore- and hindlimbs,
Exact results (in liters): .
axial_total 5295.93158
forelimb_unilateral 31.60861
hindlimb_unilateral 234.84070
total 5828.83020
As noted by the describers (and like other megaraptorans), Maip appears to be highly pneumatized. Still, in the light of work by Larramendi et al. (2021), a density much below 0.9 would not appear very likely, as not even sauropods fall below this value in their analysis. Total body mass at a density of 0.9 kg/l would be 5.2 t. Assuming a slightly higher density of 0.95, it would be about 5.5 t.
If we assume a lower density of 0.8, more in line with the previous estimates for the most highly pneumatized theropods and sauropods (e.g. Hutchinson et al. 2011, Bates et al. 2015), body mass for Maip would be about 4.7 t.
Either way, based on this reconstruction of the skeleton, it appears that Maip at least approached, and likely exceeded, the 5 ton mark, which would seem to make it comfortably the largest theropod in terminal Cretaceous South America.
References:Aranciaga Rolando, A.M., Motta, M.J., Agnolín, F.L., Manabe, M., Tsuihiji, T. and Novas, F.E. 2022. A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina. Scientific Reports 12 (1): 6318. Bates, K.T., Falkingham, P.L., Macaulay, S., Brassey, C. and Maidment, S.C. 2015. Downsizing a giant: re-evaluating Dreadnoughtus body mass. Biology letters 11 (6): 20150215. Hutchinson, J.R., Bates, K.T., Molnar, J., Allen, V. and Makovicky, P.J. 2011. A computational analysis of limb and body dimensions in Tyrannosaurus rex with implications for locomotion, ontogeny, and growth. PLoS One 6 (10): e26037. Larramendi, A., Paul, G.S. and Hsu, S. 2021. A review and reappraisal of the specific gravities of present and past multicellular organisms, with an emphasis on tetrapods. The Anatomical Record 304 (9): 1833–1888. |
|
|
|
Post by Supercommunist on Jun 1, 2024 11:32:09 GMT 5
|
|
|
|
Post by Supercommunist on Jun 3, 2024 0:21:16 GMT 5
|
|
|
|
Post by Infinity Blade on Sept 10, 2024 21:54:00 GMT 5
|
|
