Whilst this may not be the most important thing on inat I personally think it is important to discuss, Inat doesn’t have the correct classification on some extinct species like otodus megalodon which on inat is reported as carcharocles megalodon. I think it is important to correctly classify these groups in the most scientificily accurate groups possible and well megalodon isn’t.
The group megaraptora (the theropod dinosaurs) is also in a incorrect grouping as well it isn’t recognised at all, being not present in any regard. While it may be a contested group currently it really shouldn’t matter as the rest of therapoda are all in separate, yet even groups no matter where there they sit in the therapod family tree. This group as well as most other groups of theropod should be updated to keep to current scientific understandings, in order to keep a reliable representation of all families and orders.
I admit I might not be the best in this topic as i might be missing a lot about this topic, but i still think it is important that this issue is explored and adressed
i believe that the usual way to suggest taxon changes is to go to the taxon page and flag it for curation. i think that would apply even in cases of extinct taxa. in fact, megalodon already appears to have a pending taxon change: https://www.inaturalist.org/taxon_changes/97623, and you can discuss in the comments section on that page.
In general, curators are expected and encouraged to avoid adding extinct taxa unless they fit into our preexisting taxonomy (extinct species in an extant genus, for example). Your suggestions for Therapoda would require sweeping changes that would provide minimal benefit, at least in the context of iNaturalist. Remember, iNat is not a provider or authority of taxonomy, but a tool for posting observations of identified organisms.
As for megalodon, you’ll have to find a curator familiar with shark taxonomy to correct it. The current swap is not set up correctly (species into genus) so it’ll need to be edited and the taxonomy of those groups revised. Clearly, users are intent on posting observations of fossilized shark teeth, so megalodon as a taxonomic entity does provide some benefit for the categorization of those observations.
iNaturalist is about observing living things so maintaining extinct clades in the taxonomy is not a curation priority. However, Extinct clades are tolerated provided:
They fit into the taxonomic backbone - e.g. the Passenger Pigeon belongs to the extinct genus Ectopistes which nests neatly within the extant family Columbidae. But accommodating the extinct “mammal-like reptiles” would require changing the backbone by inserting new nodes between the existing Subphylum Vertebrate and Class Mammal nodes or breaking up traditional (but non-monophyletic) basal groups used by Catalog of Life and GBIF such as reptiles. We prioritize taxonomic backbones that match external references over ones that can accommodate extinct groups.
The extinct nodes and all of its descendants are marked as Extinct by adding Extinct conservation statuses. Since this is a lot of work, curators may prefer to rather ungraft or inactivate extinct clades rather than do the work involved in marking the entire clade as extinct. If you care strongly about including an extinct clade, please be prepared to do this work yourself.
Unfortunately the sparseness of extinct taxa on iNat often means the taxonomy and clades assigned to these taxa are incomplete and, while not inherently inaccurate, less likely to be reviewed by nearly as many people as living clades/taxa. It’s no secret that extinct taxa are heavily overshadowed by living taxa on this site - and with good reason. For example, the Taxonomy of the clade Pterosauria in Taxa Info is incomplete because why would a site dedicated to the documentation of living organisms devote so much time on the endless taxonomy on the countless extinct clades? Taxonomy of extinct life changes often, and these changes aren’t easy to keep up to date at all times - even Wikipedia isn’t immediate with these taxonomic shifts.