Norselaspis study: clueless about gnathostome origins
The Miyashita et at 2025 headline called Norselaspis
(Fig 1) “the sister group of jawed vertebrates.”
This is incorrect.
Figure 1. Norselaspis images from Miyashita et al 2025. Extended areas and colors added here. Those unlabeled cyan colored, extendible oval elements surrounded by ‘teeth’ are homologous with similar elements with ‘teeth’ in baby sturgeons (Fig 3). Apparently the authors overlooked this structure because it was not labeled.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif?w=112″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif?w=383″ class=”size-full wp-image-94072″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif” alt=”Figure 1. Norselaspis images from Miyashita et al 2025. Extended areas and colors added here. Those unlabeled cyan colored, extendible oval elements surrounded by ‘teeth’ are homologous with similar elements with ‘teeth’ in baby sturgeons (Fig 3). Apparently the authors overlooked this structure because it was not labeled.” width=”584″ height=”1563″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif?w=584&h=1563 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif?w=56&h=150 56w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif?w=112&h=300 112w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis588-1.gif 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. Norselaspis images from Miyashita et al 2025. Extended areas and colors added here. Those unlabeled cyan colored, extendible oval elements surrounded by ‘teeth’ are homologous with similar elements with ‘teeth’ in baby sturgeons (Fig 3). Apparently the authors overlooked this structure because it was not labeled.
Taxon exclusion
marred this otherwise excellent report. The authors did not realize that jawed vertebrates had several origins in the LRT, not just one.
Moreover, and ironically,
the authors did not realize that osteostracans (including Norselaspis, Fig 1) are basal only to sturgeons (Figs 2, 3), which feed with extendible ventral tubes, not jaws.
Figure 5. Sturgeon mouth animated from images in Bemis et al. 1997. This similar to ostracoderms, basal to sharks.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif?w=584″ class=”size-full wp-image-51432″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif” alt=”Figure 5. Sturgeon mouth animated from images in Bemis et al. 1997. This similar to ostracoderms, basal to sharks.” width=”584″ height=”393″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif?w=584&h=393 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif?w=150&h=101 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif?w=300&h=202 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/sturgeons_mouth_animation588.gif 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 2. Sturgeon mouth animated from images in Bemis et al. 1997. This similar to ostracoderms, basal to sharks.
Miyashita et at 2025 reported,
“Here, using synchrotron-based X-ray microtomography on the model osteostracan Norselaspis glacialis, we reveal derived gnathostome traits straddling a uniquely ossified head–trunk interface in this jawless fish. The inner ear of Norselaspis shows sensory elaborations (enlarged pars inferior and sinus superior) acquired well before the origin of jaws.“
Be wary of phrases like ‘uniquely ossified’.
In evolution there are always similar and precursor structures.
Figure x. Medial section of Acipenser (sturgeon) larva with temporary teeth from Sewertzoff 1928.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg?w=584″ class=”size-full wp-image-51925″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg” alt=”Figure x. Medial section of Acipenser (sturgeon) larva with temporary teeth from Sewertzoff 1928.” width=”584″ height=”376″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg?w=584&h=376 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg?w=150&h=97 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg?w=300&h=193 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2020/12/acipenser_larva_teeth588.jpg 590w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 3. Medial section of Acipenser (sturgeon) larva with temporary teeth from Sewertzoff 1928.
The authors concluded,
“the vertebrate jaw—often considered the functional driver for ‘gnathostome’ innovations—evolved instead as a follower to the sensory enhancement, increased cardiac output and greater locomotory control now inferred in the jawless sister group.”
This is also incorrect for reasons listed above.
Figure 5. Two extant sturgeons, Acipenser and Pseudoscaphirhynchus, compared to the extinct heterostracan, Hemicyclaspis, a close relative to Zenaspis in figure 4.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg?w=584″ class=”size-full wp-image-82471″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg” alt=”Figure 5. Two extant sturgeons, Acipenser and Pseudoscaphirhynchus, compared to the extinct heterostracan, Hemicyclaspis, a close relative to Zenaspis in figure 4.” width=”584″ height=”396″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg?w=584&h=396 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg?w=150&h=102 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg?w=300&h=204 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2023/11/acipenser-brevistrostrum588-1.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 4. Two extant sturgeons, Acipenser and Pseudoscaphirhynchus, compared to the extinct osteostracan, Hemicyclaspis.
Without a comprehensive and valid phylogenetic context,
these authors were clueless with regard to taxa at the origin of jaws and taxa at the origin of sturgeon with their ventral extendible tubes.
Build your own large reptile tree (LRT, 2338 taxa) to confirm, modify or reject this hypothesis of gnathostome origins.
Better to have too many taxa in analysis than too few.
Be wary of current paleo textbooks. Authors, referees and editors all depend on these, but many chapters are now out-of-date due to traditional taxon exclusion.
References
Miyashita, T., Janvier, P., Tietjen, K. et al. 2025. Novel assembly of a head–trunk interface in the sister group of jawed vertebrates. Nature. https://doi.org/10.1038/s41586-025-09329-9
wiki/Hemicyclaspis
wiki/Osteostraci
Publicity figure. Illustration of Norselaspis.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg?w=226″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg?w=584″ class=”size-full wp-image-94068″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg” alt=”Publicity figure. Illustration of Norselaspis. ” width=”584″ height=”774″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg?w=584&h=774 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg?w=113&h=150 113w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg?w=226&h=300 226w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/08/norselaspis-illustration588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Publicity figure. Illustration of Norselaspis.
Publicity
A googly-eyed fish could upend evolutionary history
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Source: https://pterosaurheresies.wordpress.com/2025/08/08/norselaspis-study-clueless-about-gnathostome-origins/
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