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The Biggest Ammonite Fossil Ever Found Was A Whopping 1.8 Meters That means the largest ammonites were similar in size to giant sunfish when they were alive Rachael Funnell, IFL Science, June 9, 2023 Parapuzosia seppenradensis - Wikipedia A related article is: Tohoku University Exhibits Rare Giant Ammonite Fossil By Iednewsdesk On Aug 29, 2023 Yours, Paul H.

The Biggest Ammonite Fossil Ever Found Was A Whopping 1.8 Meters Rachel Funnel. IFL Science, June 9, 2023 Parapuzosia seppenradensis An open access paper is: Ifrim, C., Stinnesbeck, W., González González, A.H., Schorndorf, N. and Gale, A.S., 2021. Ontogeny, evolution and palaeogeographic distribution of the world’s largest ammonite Parapuzosia (P.) seppenradensis (Landois, 1895). Plos one, 16(11), p.e0258510. Another paper is: Scott, G. and Moore, M.H., 1928. Ammonites of enormous size from the Texas Cretaceous. Journal of Paleontology, pp.273-279. Yours, Paul H.

One of the wonderful things about this hobby is that the adventures are always surprising, and this weekend proved that yet again. ...................................................... A few days ago, I decided that it's time to branch out around austin a bit. Over the past few months, I've discovered a few "safe spots", where I know I can usually find something, but none of those spots center around one of the most productive formations in Central Texas - The Eagle Ford. Furthermore, I was inspired by some of the marvelous collections from some of the locals here, who have pulled many of their specimens from Travis County's Eagle Ford exposures. So, it was time to get to work. I decided that, specifically, I wanted to romp around localities where the Bouldin Flags member of the eagle ford was exposed, with the hope of running into Ptychodus or Mosasaur material. Online, I found an old geology guidebook, written in the 70's by the University of Texas. It actually was extremely detailed about where to find many members of the Eagle Ford, and listed three absurdly specific and trivial locales for the Bouldin Flags. However, since it was written in the 70's, some of the street names they mentioned changed slightly or straight up didn't exist anymore, and one of them I suspect was covered with development. So, it took some creative investigative work until I thought that I found a good spot to act on - A drainage ditch next to a railroad deep in Austin. I arrived with high hopes that were soon dashed - a very large homeless camp was parked all along the stretch that was mentioned (that's Austin for ya). The railroad itself was quite elevated, with the ditch leading down low, all the way to a creek. Determined not to waste a trip, I simply decided to find a different access point and explore the creek - maybe there were more exposures if I just walked a quarter of a mile down. I eventually found myself looking at some bulgy, unstable looking limestone banks, like the one above, but many more pronounced in their texture. It was a long, slow, sweaty walk, up and down. Litter from the homeless camp upstream crowded some parts of the creek, and I was also getting rather hazy - I wasn't exactly sure what I was looking for, and there was a lot to see. (pardon the upcoming image quality, most are screenshots from the videos I took) (above: an aesthetic little slab) On my last pass back however, I saw the unmistakable shape of an ammonite protruding from the ground - but it was far larger than any ammo I've ever seen. Below is the insitu and after wiggling it out - these are size 11 shoes, for reference It took a while to pick my jaw up from the rocks - this was crazy! I was conflicted though - where on earth would I put the thing?!? After a mental tug of war that lasted exactly 2 seconds, I decided that I couldn't bear the thought of leaving it, knowing that the creek will eventually just wither this big ammo chunk into nothing. So I hoisted the heavy brute onto my shoulder, and endured the walk back. Once on the street, the strange mud covered college kid lugging a big rock around in the middle of the city got some strange looks. ---------------------------------------------------------------------------------- Once it was posted in Fossil ID, @JohnJ was quick to identify it as a Parapuzosia bosei or Pachydiscus sp. He also pointed out that it looked like I'd wondered my way into the Austin Chalk, but honestly, I can't complain with a find like this. @erose also made a great suggestion for a local geology guidebook, so maybe the Bouldin Flags member won't be elusive forever! Final notes: Between both ID's, I settled on Parapuzosia bosei (partly because they're a little cooler in my mind, lol), and it makes for some interesting comparisons. For example - the largest species of the Parapuzosia genus came from Europe, and I found some interesting tidbits on them. Since bosei is in the same genus though, I decided it is reasonable to scale some of the calculations that exist for their European counterparts. For example - what's given is that the largest European species of Parapuzosia reached about 2.55 meters in diameter, whereas bosei apparently reaches the neighborhood of 1.3 meters. What's also given is that these large European species, in their prime, would hold about 700 litres of air in their shell to stay buoyant, and that the organism inside could've weighed around 751 kg. If we use that info and scale it down via a simple proportion, we could probably make reasonable estimations for our Texas counterpart, the bosei. Those would mean that a large bosei could hold ~ 357 litres of air in it's shell, and would've weighed ~383 kg without its shell - that's 844 lbs of pure cephalopod! Provided, this is all based on the assumption that European and American members of the genus are similar, but you get my drift. Anyway, this was a pretty cool day. I think I now have a hopeless obsession with gigantic ammos. A change of scenery from sharks at least!