Wednesday, August 23, 2023

SearchResearch Challenge (8/23/23): What's that in the belly of the Redondasaurus?

 I looked at the Phytosaur in real shock... 

Because there, in the dinosaur hall of the Carnegie Museum of Natural History in central Pittsburgh, was what looked to be a massive crocodile.  

This is Redondasaurus bermani. It was huge and utterly evil looking, clearly a watery death machine that was 6.4 m (21 feet) long, and lived in the rivers and swamps of Triassic North America some 252-201 million years ago.


I've seen lots of assembled skeletons before.  It was big and carnivorous, but as I stood in front of the skeleton, I noticed something that I don't think I'd seen before.  

See that collection of what look like ribs in its belly?  

Here's a close-up shot: 

See what I mean?  There is the backbone above, with a lot of ribs hanging off the vertebrae.  You can easily see the massive leg bones and feet. 

But there, hanging below the backbone and ribs is something else--a kind of basket of upward pointing ribs that seems attached to the sternum.  

I don't know that I've seen that on any other animal.  Or have I just not been paying attention?  

Naturally, this led me on a merry SRS quest, which condensed into these two Challenges for you: 

1. What do you call that thing in the chest and belly of the Redondosaurus bermani?  

2. Do other animals have this thing now, or was it just an Age of the Dinosaurs skeletal feature?  

I've found the answer now after a bit of quick searching on my phone while standing in front of the beast.  I have to say, I was pretty surprised by the answer to Challenge 2.  

Another surprise was learning that the Redondosaurus is actually NOT related to any living crocodiles or alligators?  It was, as they say, a "Late Triassic clade of crocodylian-like predators."  That is, there were other kinds of Redondosaurus (collectively called the Phytosaurs) that filled the ecological niche that crocs and alligators fill in todays swamps.  They had short legs, wide, heavy bodies with rows of armored scales, long tails, and long toothy snouts. The only obvious difference between crocodiles and phytosaurs is that crocodiles have their nostrils at the ends of their snouts, and phytosaurs had them on raised hump in front of their eyes. Despite the strong similarities between phytosaurs and crocodiles, the two groups are not closely related.

Let us know what answers you found to this week's Challenge.  Of course, tell us HOW you found them.  We all want to learn from your search strategy.  

Hope you find this as interesting and entertaining as I did.  

Keep searching! 


  1. I saw that exhibit just a few weeks ago when I was at CMU for DIS! Likewise I was impressed, but I didn't notice the belly ribs at the time. A bit of searching suggests they are officially called "gastralia" and modern crocodiles possess them. Interesting!

    1. And do you remember how you searched for them? What query finally worked?

    2. Yes! I looked up this creature in Wikipedia, but that article didn't seem to mention the ribs. So I jumped up one level in the taxonomy to check out the article on phytosaur. That article contained a mention of "gastralia (abdominal ribs)" when describing differences from crocodiles. The link to gastralia contained a photo of dino ribs that looked like the original query photo. That article was a little hedgy on whether modern crocodiles have gastralia so I confirmed that with a Google query.

  2. the serendipity/unintended consequences of attending conferences, eh… curiosity is key - lesson: keep breathing.
    building off Mr. Luther's answer… about breathing
    Sue revamped in Chicago:
    Archosaur Respiratory System :
    National Library of Medicine:
    A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs
    "These dinosaurs sported a costovertebral joint and the birdlike bony "ceiling" of vertebrae and ribs that helps keep the lungs rigid. All of this suggests dinos had the same kind of efficient respiratory organs as birds, the team concludes."
    birds -
    "Gastralia are absent in living birds, considered functionally redundant in the presence of the large ossified sternum that characterizes Neornithes (Claessens, 2004), thus bridging the possibility that the large gastral basket in Sapeornis may have functioned as a compensatory feature in the absence of a sternum and ..."

    related to the diaphragm in humans
    does Jack Reacher have gastralia? (a Pittsburgh ref )

  3. dermal ossifications
    gastralia in matrix:
    locomotion -

  4. used [Dinosaur gastralia and their function in respiration]
    some video that might be helpful -
    from here:

  5. toothy fellow
    background info

  6. casting a net…
    wiki on Redondasaurus:
    Ghost Ranch
    a different Colbert:
    Japanese database refs:
    see authority control for Cohen - interesting

  7. Searched [Redondasaurus Bermani ribcage]

    Larry Rinehart, preparator at NMMNH
    (New Mexico Museum of Natural History) comment at the end could be of interest to others too. Even when it was made in 2011

    1. I didn't know about gastralia. However, after reading the comments, searched [which animals have gastralia]

      Why Do Animals Have Soft White Underbellies? (2013)

      Countershading and then But what explains the softness?

      Gastralia provided not only some measure of physical protection but also attachment points for abdominal muscles and other tissue....Perhaps the birds illustrate why other species lost or never bothered with abdominal bones. Extra bones or armor take a lot of calories and calcium to grow and maintain...

      With [today i found out gastralia]

      Sue the T. Rex was added with gastralia. A comment from 4 years ago says:

      According to the museum’s website, “ [the gastralia] helped T. rex breathe by pushing air in and out of the lungs (we humans have a diaphragm for this purpose).”

      Apparently, gastralia form part of the shell of turtles. Mentioned in other comment.

    2. Thank you, Remmij. When read the comment, didn't think about searching Mr. Dave Berman nor Mr. Larry Rinehart and they have interesting publications to read.

    3. Visited Gastralia Wikipedia (Spanish) and there tried other "famous" languages.

      German says:

      "Dinosaur gastralia were first described by Eudes-Deslongchamps in 1838 in Poekilopleuron bucklandii , but without having recognized them as dermal bones. Therefore, Osborn's description of the gastralia of a Tyrannosaurus rex from 1906 is often cited as the first description."

  8. change of pace… it hooked me… on track
    off topic, but bike, rail and bing related…
    if you still have time to bike - and check a nice stretch of coast.
    check @ 6:55 - Shark Fin Cove, Davenport, CA - today's bing wallpaper
    saw the bing page this morning, then ran across the bike piece this evening & it mentioned Davenport & click, the bulb went off when he rode past the cove… interesting chance connection & bits of history; e.g., the Pelton Wheel
    an interesting blend of tech… it could be CA's "successful" high speed rail line ;^p
    can't get lost in the Late Triassic all the time - will make you forget the Phytosaur for a bit…
    btw, pretty decent camera & drone work - the drone's tracking through the trees was impressive.
    goo maps will get around Shark fin - multiple views -
    where it begins:

  9. and it pulls me back in… Redondasaurus
    cyber-oblivion: long in the tooth

  10. some background

    1. This was a fascinating time in the bone business.

  11. in situ
    for sale

  12. who knew they were in the late Humormonastic Period - 😳😉🐊
    some different images

  13. I just searched 'belly ribs t-rex' because I knew I had seen, remarked on, but not investigated the same feature when I saw a T-rex exhibition. The wikipedia article for gastrilaria was the first result (because it folded 'abdominal' into my 'belly' keyword). Then I searched 'Redondosaurus bermani gastrilaria' and then 'Redondosaurus bermani "gastrilaria" to force results with the latter, and found a couple articles confirming it's the same feature in this animal.

    And the original wiki page for gastrilaria mentions they're found in modern crocodilians and tuatara.

    1. interesting find on the tuatara - brings it to the current day…
      from wiki:
      "The tuatara has gastralia, rib-like bones also called gastric or abdominal ribs,[45] the presumed ancestral trait of diapsids. They are found in some lizards, where they are mostly made of cartilage, as well as crocodiles and the tuatara, and are not attached to the spine or thoracic ribs. The true ribs are small projections, with small, hooked bones, called uncinate processes, found on the rear of each rib.[37] This feature is also present in birds. The tuatara is the only living tetrapod with well-developed gastralia and uncinate processes.

      In the early tetrapods, the gastralia and ribs with uncinate processes, together with bony elements such as bony plates in the skin (osteoderms) and clavicles (collar bone), would have formed a sort of exoskeleton around the body, protecting the belly and helping to hold in the guts and inner organs. These anatomical details most likely evolved from structures involved in locomotion even before the vertebrates ventured onto land. The gastralia may have been involved in the breathing process in early amphibians and reptiles. The pelvis and shoulder girdles are arranged differently from those of lizards, as is the case with other parts of the internal anatomy and its scales.[46]"