(News) A new species of Spinosaurus with a "scimitar-shaped" crest (Sereno et al., 2026).

Spinosaurus mirabilis compared to a guinea fowl (Sereno et al., 2026, p. 782). Scale bar is 20 cm for Spinosaurus, but 30 cm for the guinea fowl:

I recently posted part 3 of my "What did Spinosaurus Look Like?" series, and now we have a new species of Spinosaurus: Spinosaurus mirabilis! While the specimen is extremely fragmentary, it possesses a new crest design, a long tibia with a thick cross-section, and the authors suggesting that Spinosaurus was a wader. Given that the lead author of this paper is Paul Sereno, I'm not surprised by this conclusion.

Sereno et al., (2026) said that S. mirabilis comes from the Farak Formation, dating from the Cenomanian-Turonian periods. This is 100-95 million years ago (p. 782 Rationale; pp. 1-2). Quick note: One of my friends on Discord said that the specimen was originally thought to have come from the Albian, but this was changed. This was about two or more years ago. Anyway, Spinosaurus mirabilis "is distinguished by a scimitar-shaped bony crest" on the top of its skull (p. 1 Abstract; p. 2 Diagnosis; p. 3 Figure 2A-B). This is different from the semi-circle-shaped crest on the skull of Spinosaurus aegyptiacus (Figure 2C-D). The crest had "neurovascular canals" in them (Figure 2F; p. 5 Discussion: Skull), which means that a "keratinous sheath" might've covered it (p. 5: Discussion: Skull). That will be fun to draw later. 

Figure 2:

A skeletal reconstruction can be seen in Figure 3. The ischium is fragmentary, but appears to have been short. The femur is extremely fragmentary, consisting only of pieces, but it appears to have been small. The majority of the tibia was preserved, and it is kinda long. A cross-section reveals that it was thick (p. 4 Figure 3A, and G-H). The tibia is 54.6 cm long (Supplementary Materials, p. 4 Table S2). The pelvic, and hindlimb, areas of this species is similar to that of S. aegyptiacus.

Figure 3:

Table S2 (Supplementary Materials, p. 4):

The specimens of S. mirabilis were found near sauropod bones, suggesting that it lived in a riparian (terrestrial) habitat. The authors concluded that S. mirabilis, and S. aegyptiacus, were waders and not divers (p. 2 Figure 1; pp. 4-5). The location of the bones are inland (p. 2 Figure 1; p. 7 Figure 5A). The authors also stated that the spinosaurid clade plotted in between wading and diving birds, yet they concluded that spinosaurids were waders (pp. 5-6 Discussion: Predatory mode). However, in Figure 4, Spinosaurus is placed right outside the diving group of birds (Figure 4 number 1) while Suchomimus is closer to the wading group (Figure 4 number 2). Figure 4 in the Supplementary Materials places all spinosaurids as being closer to waders, but there's still a few diving birds close to them though (numbers 32, 37, and 38) (p. 26). This means that the spinosaurids are close to waders, and divers. Fabbri et al., (2022) said that Suchomimus' bones were not as thick in the cross-sectional area as in Baryonyx or Spinosaurus (Figure 1), so seeing Suchomimus as a wader makes sense. This doesn't work for Spinosaurus. But, that's just my opinion. 

Figure 1:

Figure 4:

Figure 5:

Figure 4 (Supplementary Materials, p. 26) (Numbers 32, 37, and 38 are diving birds):

Spinosaurid bone density (Fabbri et al., 2022, p. 854 Figure 1):

Spinosaurus' teeth were "interdigitating" (overlapped), as seen in crocodilians, ichthyosaurs, and plesiosaurs (p. 782 Results; p. 3 Figure 2E and G; p. 5 Discussion: Skull, p. 8 Discussion: Spinosaurid evolution). I wonder if this means that Spinosaurus didn't have lips? I guess my equation of Spinosaurus to ichthyosaurs, and plesiosaurs, in part 3 of my series was kinda accurate after all. 

I do have some problems though. First, there are no forelimbs preserved for S. mirabilis. Second, the fragments of the femur still suggest that it was small (Figure 3). We already know that Spinosaurus' femur wasn't capable of carrying a 7-8-ton animal. Third, the tibia is longer for this species, but is that enough to make the animal an obligate biped? Personally, until we find a longer femur for the genus, perhaps even a longer tibia for S. aegyptiacus, then I'm gonna remain in the minority and say no. I desperately want someone to find a complete, or semi-complete, pair of Spinosaurus forelimbs! Until then, knowing what I've uncovered in parts 1-3 of my "What did Spinosaurus Look Like?" series, I'm sticking with Spinosaurus being a belly-slider on land. Fourth, the authors want to bring the point home that spinosaurids were waders. I'm not convinced. Figure 4 in the paper, and Figure 4 in the Supplementary Materials, suggest that spinosaurids were doing both wading and diving. Upon closer inspection, some like Suchomimus would've been waders while Spinosaurus would've been a diver. This backs up what Fabbri et al., (2022) showed with the cross-sections.  The thick cross-section of the tibia in Figure 3 of Sereno et al. also tells me that S. mirabilis might've been a diver, like its sister species.

I also found an interview that Nizar Ibrahim did for New Scientist earlier this month (2/6/26). Ibrahim does not believe that Spinosaurus was a wader, and thinks that Spinosaurus was a diver. I agree with Ibrahim. Ibrahim was not an author in Sereno et al., (2026). 

In summation, it's really cool to have a new species of Spinosaurus. I love the crest design. However, I'm still not convinced that it was an obligate biped, or just a wader. 

Links:
Sereno et al., (2026):
https://www.science.org/doi/10.1126/science.adx5486
Fabbri et al., (2022):
https://www.nature.com/articles/s41586-022-04528-0.epdf?sharing_token=rxUUwyZxDWQ24dJfwtIw89RgN0jAjWel9jnR3ZoTv0NEFj8DFZa3bazFWKdXldNTvT8T3daJQzYMUbPXaqso6c2KKBgthBeOpsV72_JOZHeSlOxZzzE9wUggHYItKT5ASyn5r0hTiRPfCQi_Cfe9RPf0tvCNFd3T4QXE2UU4r7wR-SYYL4_TSvBiBpniofeQoStgnv6yWzzkL81Gcy2g6hKT9nO8ozsufeY9DwX1VK-Vsw94pFBHTtBWnm2-q0bJ33Xx2cPSUh5t7T-nx3NDvtkT9MSkWBYPTw7aqWM5FRs%3D&tracking_referrer=www.sciencenews.org
-Supplementary Materials:
https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-022-04528-0/MediaObjects/41586_2022_4528_MOESM1_ESM.pdf
Nizar Ibrahim 2026 interview (New Scientist. Stock and Cossins, 2/6/26):
https://www.newscientist.com/video/2514466-have-scientists-finally-figured-out-spinosaurus/
-V2:
https://www.youtube.com/watch?v=C9DW4EgJ0zg&t=40s