There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
06-29-2020, 06:38 AM( This post was last modified: 06-25-2021, 11:22 PM by DinoFan83 )
Just going to copy down the overall methodology behind the new Spinosaurus size estimates for those who have not seen it in the other thread.
Edit 2: Look at post #19 for my current estimates. This post won't be deleted because it has a lot of information and estimates that could be useful in the future for MSNM v4047 and NMC 41852, but for the moment, we still cannot estimate them.
IMPORTANT UPDATE: As per personal communication with SpinoInWonderland, he considers his 1.86 meter estimate for MSNM v4047 to be outdated because he suspects it is based on restored material, and this almost certainly means Ibrahim's latest skeletal used restored cranial material as well given its similarity to the aforementioned restoration. This means that because the juvenile Spinosaurus skulls that were thought to be complete are actually restored, we have not found any appropriately complete and non-restored cranial material at this time to fill in the lack of overlap between FSAC-KK 11888 and MSNM v4047. Basically, although the estimates below (12260-13700+kg) for MSNM v4047 are still plausible, they cannot be confirmed because of lack in overlap with the neotype as well as a lack in gap-filling material and thus it is strongly advised to avoid estimating any size for it until better cranial material is found. The only probable adult Spinosaurus specimen that can be reasonably estimated from overlap is NHMUK R-16421, which as stated below is 10,940 kg with SpinoInWonderland's estimate of 38.7% larger than the neotype and with the new density estimate. This specimen is the average, maximum, and minimum probable adult size for the species that can be estimated at this time, and it still fits very well into Ibrahim's estimate of 10-12000 kg.
(06-13-2020, 04:37 PM)DinoFan83 Wrote: Here's a quote from SpinoInWonderland regarding the most recent information on Spinosaurus' size.
"Ibrahim et al. (2020) has a volumetric estimate for the neotype, at 3865 litres. Using a mean density of 0.95 for Spinosaurus gives a mass estimate of ~3.67 tonnes. Scaling up to MSNM v4047 (32% greater dimensions as per Ibrahim et al. 2014) yields about ~8.44 tonnes. It has been argued that the chest of the new reconstruction is too deep, but then the scapulacoracoid is also placed too far back at the chest - these might cancel each other out. Henderson (2018) got a mass estimate too low as the chest they modellled for Spinosaurus was way too narrow than was indicated by the known material."
Asier Larramendi and Greg Paul also suggest 1.05. This means 4100 kg for the neotype.
Based on the above, we get 10940 kg for NHMUK R-16421 (4100x1.387^3) based on SpinoInWonderland's work. This specimen would be 15.8 meters long based on his 11.4 meter estimate for the neotype.
Quote:As it turns out, correcting the model from Henderson (2018) gets a surprisingly large animal well in line with the estimations from Ibrahim (2020).
The model was 7 tonnes as-is, but not only does it have the ribcage only 63.4% as wide as the deepest point on the torso when it should have been a 1 to 1 width to depth ratio following the new model, the mounted skeletons, and Andrea Cau's attempts to articulate spinosaur ribs, it is also too pneumatic with a density of 0.833 when it should have been around 1, and it doesn't have the new tail which would have been around 1.5 times the mass of the old one judging by the neural spine depth.
The exact torso mass is not listed in the study so to tentatively estimate the corrected version, I'll assume the torso and tail in Henderson's model takes up roughly the same percentage of the animal's mass as SpinoInWonderland's old Spinosaurus (which was only apparently too small-headed and too elongated overall, for proportional size of each body part it should be fine).
-Pneumaticity correction: Changing the pneumaticity from 0.833 to 1, Henderson's model goes to 8.4 tonnes.
-Torso widening: Widening the torso about 57.7% (100/63.4=about 57.7) using the assumption that it was proportionally similar to SIW's old GDI (meaning a torso slightly over 55.7% of total mass), it goes up to 11.1 tonnes.
-Tail mass increase: Increasing the tail mass 50% assuming proportional similarity to the GDI (meaning a tail about 20.8% of total mass), it goes up to 12.26 tonnes*, which compares favorably with the other estimations here.
Quote:I have an alternate size estimate for MSNM v4047 compared to what Ibrahim's suggestion would yield. It is based on the discrepancy between the new skull reconstruction in Ibrahim et al. 2020 for the neotype (122 cm) and SpinoInWonderland's estimate for MSNM v4047 (186 cm). Given that FSAC-KK 11888 and MSNM v4047 do not overlap, this is based on general similarities between the full skull reconstructions, and it looks to me as though both have been restored using criteria that was very similar if not the same.
Comparing both of them, it seems to me that the size difference between the 2 specimens is very likely 52.5% instead of 32.5%, and this is further supported by the fact that they are about the same shape; MSNM v4047 does not look any more elongate which would be misleading to go off of were it the case.
This would then result in an animal of at least 13.7 tonnes (assuming a density of at least 1 for the 3,864 liter neotype), and it would be some 17 meters in length taking the mean of the length estimates from Ibrahim (10.93 meters) and SpinoInWonderland (11.4 meters).
