This post is my third entry in my “Invertebrates in Paleomedia” series, covering extinct invertebrates featured in documentaries, giving an overview of their accuracy and some of the surrounding context behind their depictions.
Yesterday I covered Life On Our Planet, and before that I covered the entire Walking With… series, which can be read below -
https://invertposting.blogspot.com/2024/04/the-invertebrates-of-walking-with.html
https://invertposting.blogspot.com/2024/04/the-invertebrates-of-life-on-our-planet.html
This entry covers Sea Monsters – A Prehistoric Adventure, which is renowned as one of the best pieces of paleomedia and for good reason; it gives a full depiction of an environment with incredibly up-to-date depictions of the fauna (which have generally aged well, but are not perfect by current standards), a likeable and easy to digest format with a wonderful story all based directly off fossil evidence, and a stunning score.
It’s great! And, most relevantly here, it features a few interesting invertebrates!
Six species are featured in the documentary – an ammonite (unnamed, may be Placenticeras), Baculites, Tusoteuthis, Uintacrinus, jellyfish, and Inoceramid clams. They unfortunately don’t get too much screentime, and the companion book doesn’t elaborate on much else, so I’ll just go off of what I’ve got.
Starting off with the coiled ammonites, they are pretty good depictions for the time. They have an operculum, which we know ammonites did not have, as discussed in this snippet below from my Walking With… post
We don’t know much about ammonite soft tissue, but we do know they had eight arms and two larger tentacles, lined with hooks, similar to those of squid (Smith et al. 2021). The presence of an ink sac is tentative at best; at the time it was thought to be the case, but this interpretation has since been questioned, as seen in Klug and Lehmann, 2015
The other ammonites, Baculites, get a beautiful scene directly supported by scientific evidence. Baculites definitely spawned and lived close to the seabed, something backed up by isotope studies (Sessa et al. 2015), and in very large numbers, something suggested by many mass associations of remains. The Baculites are feeding on plankton, something directly shown in a specimen found with pelagic isopods and larval gastropods in its jaws (Kruta et al. 2011).
Bioluminescence is an interesting and reasonable bit of speculation, especially because coeloids (their closest relatives) tend to have that ability.
There is one shell-less cephalopod featured – the supposed “giant squid” Tusoteuthis. This depiction is incredibly outdated, unfortunately. I’m primarily gonna be referencing Tyler Greenfield’s wonderful blogpost on reconstructing this cephalopod, sources for all the critiques can be found within - https://incertaesedisblog.wordpress.com/2020/07/03/reconstructing-fossil-cephalopods-enchoteuthis-tusoteuthis/
The enchoteuthines were related to extant octopi, not squid, and thus would’ve lacked the long pair of tentacles that aided in great size estimates. Instead, the general anatomy of these cephalopods would’ve been analogous to the Humboldt squid (Dosidicus gigas) due to ecological similarity, which results in a smaller (albeit still large) size.
A juvenile is seen later on, swimming amongst a group of Uintacrinus. Uintacrinus is an odd crinoid because it seems to lack a stalk; some older interpretations suggest that its calyx was filled with gas and it floated along, dredging its arms along the seafloor, but this is likely untrue, as summarized below in this blogpost by Christopher Taylor - http://coo.fieldofscience.com/2010/02/crinoids-of-open-seas.html
Other, more modern art depicts it as swimming through the
water column like a jellyfish, but as shown above this was also likely not the case.
So, Sea Monsters’ depiction is pretty good since it has them mouth-up and not
actively swimming; very happy to see an extinct echinoderm!
In this sequence there are also some jellyfish, live-acted by good ol’ Aurelia. There are no fossil jellyfish known from the WIS as far as I can tell, but they almost certainly would’ve been there. They’re depicted as prey for the giant protostegid Archelon, which is a common practice due to pulling traits from the extant leatherback sea turtle, the largest turtle alive today, but Archelon’s beak would’ve been suitable for crushing so it may have also (or only) fed on hard prey like ammonites.
Inoceramid clams are briefly seen on the seafloor when the main Dolichorhynchops dies. Not much to say on them here, but I will soon when I cover Prehistoric Planet and an adjacent personal project.
Overall, the invertebrates have arguably aged the worst in this documentary, but they still range from fairly reasonable for the time to the single best depiction of them in media. For a group that gets only a minute or so of screentime, they’re very interesting and obviously a lot of care was put in to them, which I’m very happy to see.
If you haven’t watched Sea Monsters you definitely should, I stand by the statement at the beginning that this is one of the best pieces of paleomedia out there - https://www.youtube.com/watch?v=3IvQXqN9ex0
Hoping to cover Prehistoric Planet next, but that will likely take some time. My next post will likely be covering the basics of my speculative evolution project I’ve been working on so stay tuned, thanks for reading!
