Sunday, November 27, 2022

Musings on Hanyusuchus

Every year a handful of new croc taxa are described. If you're strictly in this business for the dinosaurs, you ought to see what the croc side of Archosauria has been up to from time to time; they were quite versatile in palmier days. Even though they aren't quite as diversified as they used to be, it turns out they had hitherto-unsuspected tricks up their sleeves even as recently as a few hundred years ago. This spring a new genus and species of gavialid was described from the Holocene of south China: Hanyusuchus sinensis. This is fascinating, for many reasons. The obvious is that here we have a species of [insert expletive of choice] 20-foot-long gavial that existed up to perhaps a few hundred years ago in full contact with one of the most thoroughly documented civilizations in history, and it was completely overlooked. It may not have gone extinct until the time of the Ming dynasty. This is something like discovering that bears in Greek and Roman mythology were actually Arctodus, only if Arctodus was the size of a pickup truck. China, of course, is noted for the extant Alligator sinensis, but although the Chinese alligator is many things, not even on its best days has it been a 20-foot-long gavial.

Figure 2(s) from Iijima et al. (2022). Depicted: Hanyusuchus sinensis (composite, scaled to holotype) and 1.8 m (5.9 ft) tall human. Not pictured: Alligator sinensis (to imagine, mentally scale the Hanyusuchus to be about the same size as the human). CC BY 4.0.

Another fascinating aspect is the namesake. Han Yu was a significant writer, philosopher, and politician of the Tang dynasty. At one point in his life, he got in trouble at court and was packed off to Chaozhou in Guangdong, southeastern China to serve as prefect. In this capacity, he issued a proclamation in 819 concerning the crocodilian population. This in itself is not remarkable, except for the audience: he issued it to the crocodiles themselves. A translation of the statement can be found here (well worth a read). The icing on the cake is that the crocodiles reportedly did as instructed and departed, although we can presume that if they *did* indeed vanish from the area, strong hands wielding metal implements (like the Bronze Age weapons that left marks on some specimens) were more important in enforcing the departure. The reader may suppose that Han Yu's action was just a quaint old-time delusion; after all, there is a long history of animals being prosecuted for crimes. However, as the author of the translation notes drily, "Tang prefects did not habitually make formal verbal addresses to the local fauna" (footnote 7, p. 60). One wonders if perhaps Han Yu, who was noted for a sense of humor, had his tongue firmly in cheek.

There's also a melancholic existential aspect to the discussion. H. sinensis was part of the fabric of life in southern China for thousands of years. Descriptions of the species can be identified in historical sources, now that we know what to look for. Dynasties, cultural flowerings and renaissances, wars, conquerors, travelers like Marco Polo and Ibn Battuta, all came and went while 6-m gavials patrolled the southern rivers. They took livestock and killed people. They were apparently very noisy, probably the source of reportedly "thunder-like sounds in the night". Then they were driven into extinction and basically forgotten for hundreds of years.

References

Iijima M, Qiao Y, Lin W, Peng Y, Yoneda M, and Liu J. 2022. An intermediate crocodylian linking two extant gharials from the Bronze Age of China and its human-induced extinction. Proceedings of the Royal Society B: Biological Sciences 289:20220085. doi:10.1098/rspb.2022.0085.

Sunday, November 20, 2022

Your Friends The Titanosaurs: Caieiria allocaudata

This edition of "Your Friends The Titanosaurs" is a little different in that not only are we welcoming a new friend, we are saying goodbye to an old friend. The latter is something that should come as no surprise; with well over a hundred species, notorious for incomplete material, some of them are eventually going to turn out to be the same.

(Also, I should have mentioned this, but I moved the external links to a separate page to conserve space on the sidebar.)

Sunday, November 13, 2022

Quick Guide to Fossils at Uŋčí Makhá Park

So I went back to Uŋčí Makhá Park last weekend and spent a couple of hours taking photos of fossils, because it makes such an ideal place to see the upper Platteville fauna. After all, a winter of freezes and thaws may not leave these new exposures looking as nice as they do now. Here's a quick guide to what can be seen there. (Let's see how many photos I can squeeze into one post, and how many species I can misidentify!)

Determining where you are stratigraphically

First of all, I'd just like to reiterate the stratigraphy. Most of the vertical extent is in the Magnolia Member of the Platteville Formation, with the upper part composed of the Carimona Member of the Decorah Shale. I'm thinking more or less the entire extent of the Carimona is exposed, based on thickness; at any rate the next thing up would be the shaly part of the Decorah, and there isn't a trace of it to be seen. I'm suspicious because the difference is just so darn clear, but at this site there is an unmistakable color change between the two units: the Carimona is the upper blue-gray interval and the Magnolia is the light tan-gray interval below. The Deicke K-bentonite is the lower and thicker of the two bentonite gaps in the Carimona. (Note that the Carimona is sometimes supplemented or replaced by landscaping, but this is pretty obvious.) As you walk from south to north, the "floor" goes up stratigraphically, so it's not all one bedding plane but a gently rising series of planes, until by the exit you're close to the color change.

The color change is quite evident here. The Deicke K-bentonite is the cut-in about halfway up the blue-gray Carimona (above the scale bar in the center of the photo).

Here we've gone north, and the floor has risen. The Deicke is still the seam in the middle of the blue-gray rocks.

Sunday, October 30, 2022

Strolling on the Magnolia Member by Hidden Falls

If you're looking for something geological to do in the Twin Cities while we're still under our unseasonably warm and dry weather, may I suggest paying a visit to the new park area above Hidden Falls? [Update, 2022/11/01: this park is called Uŋčí Makhá Park.] As part of the conversion of the former Ford Plant environs, part of the area of the creek into Hidden Falls has been daylighted. The landscaping has produced a mini-bedrock gorge that exposes significant vertical and bedding-plane surfaces of the Magnolia Member of the Platteville and the overlying Carimona Member of the Decorah.

There's nothing quite like this kind of exposure in the Twin Cities; we don't have a lot of exposed non-vertical bedrock in the first place, and this particular stratigraphic interval tends to be out of reach. The closest might be the platform below the overlook at Shadow Falls, but that's more limited in extent and has more of a stair-step profile.

Bonus points for spotting the Deicke K-bentonite.

Many of the exposed bedding plane surfaces reveal the shell beds the Magnolia is known for. The fossils are almost entirely brachiopods (with a few snails) and are represented by dolomitized molds and casts, giving them that characteristic sugary appearance.

See the little bumps? Brachs.

Enlarge for a world of brachiopods.

Here's a closer view showing a few nice examples, representing multiple species.

Also, just for fun, some of the stones used for landscaping are loaded with burrows.

If you stop by, please don't attempt to remove the fossils; it's a park, after all, and the fossils aren't really going to come off in one piece because they're molds and casts. Just enjoy the experience of walking on the seafloor without ever getting wet!

Sunday, October 23, 2022

Abbott and Costello Meet the Hyolith

I seem to have missed doing a hyolith post last year, which is really a shame and is all on me. Honestly, where else are you going to get the latest information on hyoliths? Social media? Cable news? Public radio? No, of course not! This is really a public service I'm running here, and you'll thank me for it someday. With that out of the way, what's been going on in the world of hyoliths over the past couple of years? A few thoughtfully curated highlights:

If you've ever spent time looking at the origins and relationships of gastropods, you'll be familiar with the seemingly endless debates about whether such-and-such is a gastropod or something that just happens to have a shell that looks like a snail shell (like monoplacophorans, helcionelloids, and maybe bellerophonts). We've had a bit of that with the local snail-oids, although by the Late Ordovician most of the hard cases had been cleared out. Down in the Cambrian things are more complicated. One example is Protowenella, an itty-bitty (smaller than 1 mm long) shell thing that looks kind of like a Phrygian cap. (Okay, fine, it looks like an exaggerated Smurf hat.) Is it a gastropod, a monoplacophoran, or a helcionelloid? According to Peel (2021), it is none of these. Instead, it is... a hyolith.

(Admittedly, the surprise you are feeling is probably tempered by the fact that this is a post about hyoliths, so it wouldn't have made sense for it to be a chiton or graptolite or something.)

Peel based his conclusion on the presence of a bilaterally symmetric operculum (a mineralized cap that covers the shell aperture) with features consistent with a hyolith origin. Gastropods frequently have opercula, but they aren't symmetric, and hyoliths are the only thing known to have had opercula in the Cambrian. If this referral is accurate, it would be something of an unexpected expansion of hyolith morphological talents. Hyoliths, of course, are famous for having long triangular shells with triangular cross-sections, whereas Protowenella as mentioned looks like a curled-over pointed hat.

Now let's turn from something that doesn't look like a typical hyolith but has something that *is* typical, to something that looks like a typical hyolith but is missing something expected. Hyoliths are generally divided into two groups, the orthothecids and hyolithids. Orthothecids showed up first and have a flat, retracting operculum (rather than the more complex operculum of hyolithids) and no helens (the paired spiny appendages that make hyolithids look kind of like they have wide spindly mustaches). It turns out that there are some hyoliths with hyolithid anatomy except for no helens. Liu et al. (2022) examined one such example, "Ambrolinevitus" ventricosus, an early Cambrian form from China (which they moved to Paramicrocornus, also known to lack helens). The implication is that the hyolithid body shape evolved before helens. Therefore, whatever ecological specialization was held by hyolithids over their earlier cousins, it was underway before helens appeared.

Finally, I leave you with Sun et al. (2021), a description of some beautifully preserved Cambrian hyoliths from China. Assigned to the new species Novakotheca weifangensis, they're small (less than 2 cm at most, although some have even smaller brachiopods attached) and pretty typical in shape. The neat thing about them is the preservation of mineralized soft parts of the digestive tract, interpreted as including a pharynx, esophagus, stomach, U-shaped intestine, and possible digestive gland. The anatomy is more complex than previously thought, and suggests that at least some hyoliths were not simply filter feeders.

References

Liu, F., C. B. Skovested, T. P. Topper, and Z. Zhang. 2022. Hyolithid-like hyoliths without helens from the early Cambrian of South China, and their implications for the evolution of hyoliths. BMC Ecology and Evolution 22: article 64. doi:10.1186/s12862-022-02022-9.

Peel, J. S. 2021. In-place operculum demonstrates that the Middle Cambrian Protowenella is a hyolith and not a mollusc. Alcheringa: An Australasian Journal of Palaeontology 45(4):385–394. doi:10.1080/03115518.2021.2004225.

Sun H., Sun Z., and Zhao F. 2021. Exceptionally preserved hyolithids from the middle Cambrian of north China. Geological Magazine 158(11):1951–1959. doi:10.1017/S0016756821000510.

Sunday, October 9, 2022

Compact Thescelosaurus Year Seven

Here we are at the second weekend of October, which means it's time for three things: National Fossil Day; a new sheet for The Compact Thescelosaurus; and our annual roundup of what's been added to the spreadsheet. National Fossil Day falls on Wednesday, October 12 this year, although events occur throughout the month (especially the weekends before and after), so check your nearest museum or National Park System unit for events! Our fall Park Paleontology newsletter is also up for viewing (including more fun with packrats).

Saturday, September 24, 2022

Your Friends The Titanosaurs: Ibirania parva

It's been more than half a year since our last friendly titanosaur (Abditosaurus kuehnei), but September has brought us a new saltasaur. To be precise, our guest is Ibirania parva, hailing from the late Late Cretaceous of the Bauru Basin of southern Brazil. There is always room here for a sauropod that could have been transported in a standard shipping container,* so let's begin.

*Or, heck with that, in an Amazon van—curl the neck and/or tail and 5.7 meters/19 feet of sauropod can be yours with free shipping for Amazon Prime members. Or get a horse trailer and make allowance for your curious sauropod to poke its head out the sides.

Sunday, September 11, 2022

Mbiresaurus and Tuebingosaurus

Things have picked up since late June. In the past couple of weeks, two new "prosauropods" have been published that cover both ends of the prosauropod spectrum. One, Mbiresaurus raathi, represents the early part of sauropodomorph evolution, while the other, Tuebingosaurus maierfritzorum, is close to the transition from clear-cut "prosauropods" to clear-cut "sauropods". Long-time readers will be familiar with the author's inexplicable fondness for prosauropods, so let's invite them in.

Sunday, August 28, 2022

A comment on the history of the venomous Iguanodon

There's a funny little piece of trivia attached to Iguanodon on the Internet, that once upon a time someone suggested that the famous thumb spikes were not merely wielded as pointed instruments of close-quarters defense, but may have also delivered venom. This tidbit is most readily found in the Iguanodon entry on Wikipedia, where up until recently the idea was described as coming from Tweedie (1977) and being refuted in Naish and Martill (2001) and a Dinosaur Mailing List post by Darren Naish based on the absence of any anatomical evidence (e.g., hollow spike, grooves, open tip). All in all, the whole thing just comes across like an example of an out-there Dinosaur Renaissance concept.

There is a catch, though. "Love in the Time of Chasmosaurs" recently covered Tweedie's book in two posts, but the venomous Iguanodon did not make an appearance, as documented in the comments. I vaguely remembered reading the same thing about Iguanodon back in the day, though, so I thought I'd have a look, and I already had another source in mind: "Dinosaur Mysteries", a pop-sci-type dinosaur book from 1987 (Elting and Goodman 1987). (Coincidentally enough, LITC covered this book almost nine years ago to the day in their old digs.)

Problem: while I used to have a copy of this book (in fact, I think I had two at one point, there being relatively few dinosaur books available for many relatives looking for birthday and Christmas presents in the late 1980s), I don't now. Solution: it just so happened that Internet Archive includes a copy in their surprisingly thorough dinosaur collection. I simply signed in and there I was. Right there in the Table of Contents was "The Case of the Poisoned Spike". On page 46 was this passage:

"But could the spikes have contained poison—the way a snake's fang's hold venom? One scientist thinks that poisoned thumbs might have been a good form of protection. That is a mystery still to be solved."

And there we have it: a reference to venomous Iguanodon. It has about as much substance as your typical daydream ("one scientist" would have Wiki editors reaching for their templates), but it exists. But what of Tweedie?

It turns out Tweedie does have something to say. On page 69, we read this:

"It [the thumb spike] is usually regarded as a defensive weapon but no one has explained how it could have been effective against the great claws and rending teeth of a large theropod. There are many things concerning dinosaurs that the fossil record can never tell us about. If these living animals were known to us only as fossils, who would be bold enough to suggest that the spur on the hind leg of the platypus or the spine on a sting-ray's tail were weapons charged with venom? Dinosaurs must have been very diversely adapted animals, and it is reasonable to suppose that most of the more obvious defensive devices seen among modern animals were evolved by them."

This is a fascinating piece of work. Nowhere in it does the author explicitly propose that Iguanodon had venomous thumb spikes. Read as a whole, though, the effect is that the reader is drawn to that conclusion. To me, someone involved in the writing of this book really, really wanted to include a venomous Iguanodon but either couldn't pull the trigger on stating it plainly or was argued (or edited) out of it. Did Elting and/or Goodman read this passage and come to the unstated conclusion, making Tweedie "one scientist"? Fittingly, Naish and Martill (2001) write that Tweedie "implied" this conclusion.

References

Elting, M., and A. Goodman. 1987. Dinosaur mysteries. Platt & Munk, New York, New York.

Naish, D., and D. M. Martill. 2001. Ornithopod dinosaurs. Pages 60–132 in D. M. Martill and D. Naish, editors. Dinosaurs of the Isle of Wight. The Palaeontological Association, London, United Kingdom. Field Guide to Fossils 10.

Tweedie, M. W. F. 1977. The world of the dinosaurs. Weidenfeld & Nicolson, London, United Kingdom.

Sunday, August 21, 2022

On the eating of one's words

Back in the day, when I was an undergrad at the University of St. Thomas, I was still very much a vert paleo chauvinist, just getting my toes wet in the Decorah. I'd been going through some of the old journals and textbooks, and was dismayed by the lack of coverage of vertebrates (well, dinosaurs). Everything seemed to be about invertebrates, particularly those with some kind of useful economic function (biostratigraphy) or with extensive fossil records permitting the testing of pet evolutionary hypotheses. While discussing this with my professors, I said something to the effect of "A brachiopod can't bring you love. A trilobite, maybe, but not a brachiopod."

Two decades later, I am the proud namesake of a brachiopod, specifically (in both senses) Ivdelinia (Ivdelinia) tweeti Blodgett et al. 2022: "The species name is in honor of Justin S. Tweet, paleontologist dedicated to the documentation, preservation, and study of National Park Service fossils." Thank you, Robert, Valeryi, and Vince!

A handsome fellow, isn't it? (Scale bar is 1 cm; Figure 6 in Blodgett et al. 2022).

I. tweeti comes from the Emsian-age (late Early Devonian) rocks of the Shellabarger Limestone in Denali National Park. The formation itself is also newly minted in Blodgett et al. (2022), and is part of the Mystic sequence of the Farewell Terrane. If you're not familiar with the geology of Alaska, it's almost entirely made up of bits and pieces of crust that collided with each other during the Phanerozoic. Characteristics such as biogeography have been used to reconstruct where the crustal fragments came from and the timing of their journeys. In this case, the Shellabarger Limestone brachiopods and other invertebrates show more of an affiliation to northeast Russia than to North America, indicating the fragment rifted from Siberia before arriving at what became Alaska (Blodgett et al. 2022).

References

Blodgett, R. B., V. V. Baranov, and V. L. Santucci. 2022. Two new late Emsian (latest Early Devonian) pentameridine brachiopods from the Shellabarger Limestone (New Formation), Shellabarger Pass, Denali National Park and Preserve, south-central Alaska. New Mexico Museum of Natural History and Science Bulletin 90:73–83.

Saturday, July 30, 2022

More fun with ammonoids

A few years ago I posted on the joyful eccentricities of the heteromorph ammonites, who refused to be bound by conventional notions of what ammonites were supposed to look like. Ammonoids also experimented with some interesting morphological choices in their early days. Here are a couple of examples of inspired ammonoids you might have come across scuba diving in the Late Devonian: 

Below is Parawocklumeria, looking like a Paleozoic premonition of the globigerine foraminifera (although somewhat larger).

Parawocklumeria paradoxa, Plate 19 from Wedekind (1918) (described as Wocklumeria paradoxa)

Despite the inflated appearance, Parawocklumeria is still doing the typical coiling. Another ammonoid, Solicylmenia, seems to have decided that coiling is all well and good, but it's even better when done triangularly. What exactly this taxon got out of this, I'm not sure; it seems to have worked well enough for Soliclymenia but not well enough for anyone else.

Solicylmenia paradoxa, Plate 16 from Münster (1839) (described as Cylmenia paradoxa). I realize the quality isn't great, but on the other hand it's fun to track down the original illustrations. (And yes, both chosen species here happen to be paradoxa; I wasn't being lazy with cut and paste.)

References

Münster, G. Graf zu. 1839. Nachtrag zu den Clymenien des Fichtelgebirges. Beiträge zur Petrefactenkunde 1:35-43.

Wedekind, R. 1918. Die Genera der Palaeoammonoidea (Goniatiten). Palaeontographica 62:85–184, pl. 14–22.

Sunday, July 3, 2022

Fossil Felids of the National Park Service

For this year's annual focus on a fossil group in National Park System units, I am going to pay my Internet cat tax and present a quick look at the fossil felids of the parks. If you're not familiar with the history of Felidae, it may come as a surprise that cats are a relatively recent innovation. They have only a few tens of millions of years under their collective belts, and didn't arrive in North America until Pseudaelurus in the early Miocene. (Note: barbourofelids and nimravids may give off saber-toothed cat vibes, but they aren't Felidae.)

It turns out that there are 24 NPS units with cat body or trace fossils. All of the records, unsurprisingly, are early Miocene in age or younger. The great majority are Quaternary (concerning the question of when to cut off the paleontological record, caves don't discriminate if you happen to be 11,000 years old rather than 12,000 years old, and neither do we): only seven of the 24 park units have pre-Q cats. These are Big Bend National Park, Death Valley NP, Hagerman Fossil Beds National Monument, John Day Fossil Beds NM, Lake Mead National Recreation Area, Mojave National Preserve, and Niobrara National Scenic River.

These maps are so much easier to make now that I have one file with all of the parks as points, and I can just turn them on and off. 1. John Day Fossil Beds National Monument; 2. Oregon Caves NM; 3. Lava Beds NM; 4. Hagerman Fossil Beds NM; 5. Yellowstone National Park; 6. Great Basin NP; 7. Death Valley NP; 8. Tule Springs Fossil Beds NM; 9. Lake Mead National Recreation Area; 10. Mojave National Preserve; 11. Joshua Tree NP; 12. Grand Canyon NP; 13. Chaco Culture National Historical Park; 14. White Sands NP; 15. Carlsbad Caverns NP; 16. Guadalupe Mountains NP; 17. Big Bend NP; 18. Amistad NRA; 19. Waco Mammoth NM; 20. Niobrara National Scenic River; 21. Ozark National Scenic Riverways; 22. Chickamauga & Chattanooga National Military Park; 23. Potomac Heritage National Scenic Trail; 24. Valley Forge NHP.

Geographically the sites are concentrated in the southwestern US; in fact, 15 of the sites are in Arizona, California, Nevada, New Mexico, or Texas. This seems to say something about cat biogeography, given these are mostly Quaternary sites and the NPS has a pretty good Quaternary record in terms of geographic spread. I wouldn't base a thesis on it or anything, though.

It's not stated on the map, but the Quaternary record is heavy on caves; a dozen of the records are from caves or rock shelters. These included significant records at Carlsbad Caverns NP, Grand Canyon NP, Guadalupe Mountains NP, Potomac Heritage NST (Cumberland Bone Cave), and Valley Forge NHP (Port Kennedy Bone Cave).

Most of the records are body fossils, but at least three have cat trace fossils: tracks at Death Valley NP and White Sands NP, and tracks and cave scratches at Chickamauga & Chattanooga NMP. One of these sites has yielded a track type specimen, Felipeda scrivneri Sarjeant et al. (2002) from Death Valley NP. There are also eight fossil felid species named from body fossils discovered within or potentially within NPS areas (all named before the units were established):

  • Felis lacustris Gazin (1933) from Hagerman (now Puma lacustris)
  • Machairodus? hesperus Gazin (1933) from Hagerman (now Megantereon hesperus)
  • Felis augustus Leidy (1872) possibly from Niobrara (now Panthera onca [augusta], and Pleistocene instead of Miocene in age)
  • Felis (Pseudaelurus) intrepidus Leidy (1858) possibly from Niobrara (now Pseudaelurus intrepidus)
  • Crocuta inexpectata Cope (1895) from Valley Forge (now Miracinonyx inexpectatus) 
  • Lynx calcaratus Cope (1899) from Valley Forge (now considered a synonym of Lynx rufus)
  • Smilodon gracilis Cope (1880) from Valley Forge
  • Uncia mercerii Cope (1895) from Valley Forge (now considered a synonym of Smilodon gracilis)

Attaining consensus on cat taxonomy and nomenclature can be like, well, herding cats. It doesn't help that it can be difficult to tell cats apart; see a record of "Panthera onca" at Carlsbad Caverns NP becoming Panthera atrox (Kottkamp et al. 2022), and "Puma concolor" fossils at Grand Canyon NP becoming Miracinonyx trumani (Hodnett et al. 2022; take the skull for a spin here). Nevertheless, the Quaternary sample can be divided among seven species or species groups. Three are extinct:

  • American cheetah (Miracinonyx inexpectatus and M. trumani): found at Carlsbad, Grand Canyon, Potomac Heritage, and Valley Forge
  • American lion (Panthera atrox): found at Carlsbad, Potomac Heritage, and Tule Springs
  • Saber-toothed cats (Smilodon spp.): found at Potomac Heritage, Tule Springs, Valley Forge, and Waco Mammoth

Two are still around but not this far north:

  • Jaguar (Panthera onca): found at Lava Beds, Oregon Caves, Ozark, Potomac Heritage, and Valley Forge (these are all pretty far north for something we associate with tropical jungles!)
  • Jaguarundi (Herpailurus yagouaroundi): found at Valley Forge

Finally, two are still found in the United States:

  • Bobcat (Lynx rufus, with allowance for Lynx sp.): Amistad, Carlsbad Caverns, Chaco Culture*, Great Basin*, Grand Canyon, Guadalupe Mountains, Joshua Tree*, Lava Beds, Tule Springs, Valley Forge, and Yellowstone* (*=Holocene only)
  • Cougar/mountain lion/puma (Puma concolor): Carlsbad Caverns, Chaco Culture*, Guadalupe Mountains, and Tule Springs

The most species-rich sites are:

  • Carlsbad Caverns NP (American cheetah, American lion, bobcat, cougar)
  • Hagerman Fossil Beds NM (American cheetah, Homotherium sp. [a saber-toothed cat], Lynx rexroadensis, Megantereon hesperus [or cultridens; another saber-toothed cat], Puma lacustris)
  • Tule Springs Fossil Beds NM (American lion, bobcat, cougar, saber-toothed cat)
  • Valley Forge NHP (American cheetah, bobcat, jaguar, jaguarundi, saber-toothed cat)

Of these four, the Hagerman assemblage is Pliocene, the Valley Forge assemblage is middle Pleistocene, and the other two are late Pleistocene. In the Pleistocene, at least, a robust cat assemblage may include a big lion-type cat, a saber-toothed cat, a smaller big cat (but apparently not cougars and jaguars at the same place), and a bobcat-sized cat.

Felids are relatively uncommon compared to the other big terrestrial carnivorans. Fossil dogs and bears are more widely distributed in NPS units than cats. Furthermore, all but one NPS assemblage that has cats also has dogs, bears, or both (the exception being the Pliocene tracks of Death Valley NP). These groups, though, are for another time...

References

Cope, E. D. 1880. On the extinct cats of America. American Naturalist 14(12):833–858.

Cope, E. D. 1895. The fossil Vertebrata from the fissure at Port Kennedy. Proceedings of the Academy of Natural Sciences of Philadelphia 47:446–450.

Cope, E. D. 1899. Vertebrate remains from Port Kennedy bone deposit. Journal of the Academy of Natural Sciences of Philadelphia, 2nd series, 11(3):193–286.

Gazin, C. L. 1933. New felids from the upper Pliocene of Idaho. Journal of Mammalogy 14:251–356.

Hodnett, J. P., R. White, M. Carpenter, J. Mead, and V. L. Santucci. 2022. Miracinonyx trumani (Carnivora; Felidae) from the Rancholabrean of the Grand Canyon, Arizona and its implications on the ecology of the “American cheetah.” New Mexico Museum of Natural History Bulletin 88:157–186.

Kottkamp, S., V. L. Santucci, J. S. Tweet, R. D. Horrocks, and G. S. Morgan. 2022. Pleistocene vertebrates from Carlsbad Caverns National Park, New Mexico. New Mexico Museum of Natural History and Science Bulletin 88:267–290.

Leidy, J. 1858. Notice of remains of extinct Vertebrata, from the valley of the Niobrara River, collected during the exploring expedition of 1857, in Nebraska, under the command of Lieut. G. K. Warren, U.S. Top. Eng., by Dr. F. V. Hayden, Geologist to the expedition. Proceedings of the Academy of Natural Sciences of Philadelphia 10:20–29.

Leidy, J. 1872. Remarks on some extinct vertebrates. Proceedings of the Academy of Natural Sciences of Philadelphia 24:38–40.

Sarjeant, W. A. S., R. E. Reynolds, and M. M. Kissell-Jones. 2002. Fossil creodont and carnivore footprints from California, Nevada, and Wyoming. Pages 37–50 in R. E. Reynolds, editor. Between the Basins: Exploring the western Mojave and southern Basin and Range Province. California State University, Fullerton, California.

Sunday, June 26, 2022

The doldrums

There's been a distinct lack of dinosaurian content around here for the past few months. To be honest, this is partially on my end: my own attention and energy have been elsewhere, and I haven't been all that interested in what has been coming down the pipe (I don't care if spinosaurs fished, hunted, scavenged, browsed, or got take-out). However, there is something external going on as well. With about half of the year in the books, I think it's reasonable to guess that 2022 is not going to be remembered as a banner year in the field of dinosaur paleontology. This is a predictable result of the COVID-19 pandemic: you don't just find a couple of bones in the rock and name them then and there. (Well, you *can*, but it generally doesn't go over well. Don't you at least want to prep the bones first?) Between excavation, preparation, comparative study, writing, revising, reviewing, and publishing, description of a fossil takes years. What happens when travel is greatly curtailed and museums close their doors? You've cut off those first three parts. Sure, maybe you have time to write now, but you can't participate in expeditions and excavations, you can't prepare fossils, and you can't go to other institutions to look at their specimens. The slowdown wasn't immediately evident in the literature in 2020 because there were still plenty of papers in the pipeline. With that in mind, there was still a pretty decent flow through 2021.

Then things tightened up. Looking at one measurement of activity, in 2022 we've gone through three stretches of a month or more without a new genus or species: from late December 2021 to early February 2022, mid-March to late April, and early May to the present. We're currently in the longest gap between new taxa since whatever happened (or didn't happen) between late November 2016 and early February 2017. In addition, many of the species that have been named are not known from especially complete specimens, to put it politely. I don't know about you, but I've gotten the impression that there's been some clearing out of small projects (which would make sense under pandemic conditions). This slowdown would reflect the challenges of working on research projects in 2020–2021, and it would be safe to suspect that we are in for at least a few more slow months (with the opportunity for global political and economic instability to wreak their own impacts following).

Sunday, June 12, 2022

Fusulinids: Jumbo Forams

Foraminifera are among the most abundant and best known kinds of microfossils (and they aren't exactly confined to the past, either). While it's true that many aren't microscopically microscopic, they're still smaller than is comfortable for practically any human being to study without some kind of magnification at hand. Without such, you'd be stuck squinting at sand-grain-sized things and making such helpful observations as "okay, this one looks like a stack of spheres, and this one is coiled up, and this one is... no, wait, that's an itty-bitty fish vertebra or something." And then there are some that don't require quite as much eye strain to spot.

Like these: every grain-looking thing is a foram.

Among these giant microfossils are the fusulinids (or "fusies" if you're lazy like me), the kings of the realm of single-celled organisms during the late Paleozoic. If you can see something the size of a rice grain or a grass seed, you can see a fusulinid. In fact, the comparison will give you the idea of what to look for: fusulinids tend to look like fat, whitish seeds. The Latin word "fusus" means "spindle-shaped", or "something that's long, widest in the middle, and tapering at the ends". There's your fusulinid.

And there's another, and another... These are getting to around 3 mm long, or a bit more than a tenth of an inch. (Note also what looks to be a sliver of a trilobite pygidium near the center.)

During their heyday, fusulinids could be so abundant that their tests (shells, basically) could more or less make up sediment beds. The resulting rocks are a bit monotonously fossiliferous, as fusulinids tended to look the same on the outside. The interior architecture of chambers is how different species are distinguished, so even though you can see them without needing a microscope, you're going to need one to tell them apart. (Plus the grinding and polishing and all that jazz.) "Why bother?", you may ask. Well, it turns out that the geologically rapid turnover of fusulinid species makes them great biostratigraphic indicators in some places where people are keenly interested in subterranean resources (like the Permian oil fields of Oklahoma and Texas). Know the fusulinids, know the rock; know the rock, know the resources.

Zooming down to an even closer look, we can see that many of the fusulinids have a "perforate" appearance, which is the result of weathering exposing some of the internal chambers. Although most of the forams are seen lengthwise, there are some cross-sections scattered throughout, showing rings of chambers.

The particular examples in these photos come not from in situ outcrops, but building stone. The rock is Cottonwood Limestone used in historic structures in Kansas, and although there are other fossils, the fusulinids are by far the most abundant. The Cottonwood is early Permian in age (Wolfcampian stage in the grand old North American series), so at this point the fusulinids had a few tens of millions of years left to flourish before bowing out at the end of the Permian. According to my old copy of "Invertebrate Fossils" by Moore, Lalicker, and Fischer (1952), this would most likely represent the Pseudoschwagerina zone.

The stairs are made of forams! (No, it doesn't have the same ring as "The floor is lava!", but you *are* walking on the bodies of millions of fossilized amoeba things...)

Sunday, May 29, 2022

Recent Work from the National Park Service Paleontology Program

My day job is with the Paleontology Program of the National Park Service, and I thought you might like to see some of the work we've put out over the past few months. First up is the Spring 2022 issue of the Park Paleontology newsletter. For this issue, we have articles on:

Next, a couple of articles have just come out in the latest volume of the New Mexico Museum of Natural History and Science Bulletin series, both focused on Quaternary cave paleontology of specified parks in the southwest. Hodnett et al. (2022) describes previously overlooked bones from Grand Canyon National Park as specimens of the "American cheetah" Miracinonyx trumani. Meanwhile, drawing on the Carlsbad Caverns National Park paleontological inventory published a few years ago, Kottkamp et al. (2022) discusses the Pleistocene vertebrate record of the park's various caves.

Finally, public versions of our four latest park-specific paleontological inventory reports are also available to view and download. For just four parks, they feature a wide range of types of fossils, geology, and geography. They are:

References

Hodnett, J. P., R. White, M. Carpenter, J. Mead, and V. L. Santucci. 2022. Miracinonyx trumani (Carnivora; Felidae) from the Rancholabrean of the Grand Canyon, Arizona and its implications on the ecology of the “American cheetah.” New Mexico Museum of Natural History Bulletin 88:157–186.

Kottkamp, S., V. L. Santucci, J. S. Tweet, R. D. Horrocks, and G. S. Morgan. 2022. Pleistocene vertebrates from Carlsbad Caverns National Park, New Mexico. New Mexico Museum of Natural History and Science Bulletin 88:267–290.

Sunday, May 15, 2022

Rockfall

One of the characteristic aspects of the Mifflin Member of the Platteville Formation is its habit of planar jointing. The faces of outcrops often look like someone took a rock saw to them. Nor are they necessarily single flat planes; sometimes joints intersect to form sharp angles. The heavy thunderstorms the previous week inspired a large chunk of Mifflin outcrop to collapse along intersecting joints.

Tumbled down

The joint planes did not form overnight, which can be seen by the amount of roots and soil in the new outcrop faces. There were some pretty big roots in there as well, but whatever tree(s) had once produced them is long gone.

A view into the wedge more or less along one of the two joints.

This particular rockfall was about as polite as possible, occurring not at the top of a stereotypical 30-foot bluff but from a much lower bluff, adjacent to a bike path. The orientation of the wedged stack shows that it toppled out of its former position. The top of the stack is therefore farthest from the bluff. Perhaps it failed at the base first, due to poor support from the Pecatonica, then flopped over.

History going from left to right

Saturday, April 30, 2022

Synchronicity of Large Crinoids

I was recently out of town for work, and one of the things I saw was Middle Pennsylvanian-age building stone with stem segments from large crinoids:

Big ol' crinoids

It's like bony fingers strewn on the ground

You'd think with all this stem, there'd be a calyx somewhere, but no dice

At a shade over 1 cm (about 0.4 in) in diameter, the columnals are quite a bit bigger than garden-variety columnals, but still are well shy of world champ columnals, which reportedly exceed 2.5 cm (1 in); certainly much bigger than anything in Minnesota, right?

Yes! Time for the ironic photo!

Only yesterday, less than a week after returning from the above trip, I was visiting a couple of Decorah Shale sites and came across the above specimen. I happened to be caught short of a traditional scale bar, so you will have to take my word that the fingernail of the above finger is 1.1 cm (0.43 in) across at its widest point. Therefore, that columnal is 1.5 cm (0.59 in) across, which is pretty darn big for anything in the Decorah except for certain trilobites. In fact, it made me wonder if the stone might be a ringer transported from another formation, by glacier, river, or what-have-you. (Not impossible at all; here's a neat report on all kinds of exotic rocks and fossils found in Mississippi gravel, including Lake Superior agates and Sioux Quartzite; closer to home, a piece of an Upper Cretaceous ammonite was once found at the Brickyard, as related in Cobban and Merewether 1983:19.) However, the chunk shows no evidence of transport, and lithologically it looks the same as any piece of thin limestone eroded out of the Decorah. Were it not for the great honking columnal, I wouldn't have thought twice about its legitimacy. (I wouldn't even have thought once!) My guess is that this particular specimen originated from higher in the formation than the stuff I usually see, or that great honking crinoids were a very minor part of the Decorah fauna and this just happens to be my first encounter.

References

Cobban, W. A., and E. A. Merewether. 1983. Stratigraphy and paleontology of mid-Cretaceous rocks in Minnesota and contiguous areas. U.S. Geological Survey, Washington, D.C. Professional Paper 1253.

Sunday, April 10, 2022

Mitchell Caverns

Back in the fall of 2021, I made a work visit to Mojave National Preserve, located logically enough within the Mojave Desert of southern California. While there, I had the opportunity to tour Mitchell Caverns. Mitchell Caverns is in the unusual position of being part of a state land parcel (Mitchell Caverns Natural Preserve or State Natural Preserve, depending on the source), entirely surrounded by another parcel of state land (Providence Mountains State Recreation Area), which is itself surrounded by a National Park Service unit (Mojave National Preserve). For good measure, the cave system is also a National Natural Landmark. It's parks all the way down in the Providence Mountains. (To be fair, the natural preserve designation is kind of a map artifact; it's not really distinct from the state recreation area.)

Sunday, March 27, 2022

Detour into Choristodera

This week a paper on unusual prehistoric aquatic reptiles was published. I am speaking, of course, of Brownstein (2022) on choristoderes. (If you thought it was going to be spinosaurs, you must be new around here!)

We have a soft spot for choristoderes here at Equatorial Minnesota Towers, even if they rarely rate so much as an "and also featuring Champsosaurus" credit in sci-pop culture. Brownstein (2022) includes the classic Champ but is more focused on the short(er)-faced choristodere Simoedosaurus, although under a fresh coat of taxonomic paint: the North American species S. dakotensis is moved to the new genus Kosmodraco on the grounds of anatomical differences and differences in time and place from the type species, European S. lemoinei. It also gets a new friend, K. magnicornis. Which said, sure... but the species of Kosmodraco still clade more closely to Simoedosaurus than to anything else, so if your genericometer was so tuned, you could still include them in Simoedosaurus with a clear phylogenetic conscience. (There are a lot of anatomical differences between the two genera. My only quibble with Kosmodraco is that it's an awfully pretty name for a choristodere; it sounds more like an an extravagantly crested pterosaur. Meanwhile, Champsosaurus itself is still secretly a taxonomic booby trap waiting to be sprung. Sooner or later someone is going to do something with the various species that is entirely legal by the rules of taxonomy and yet manages to displease everyone else.)

The type skull of Kosmodraco magnicornis. It'll take a moment to orient yourself: the bitey part is surprisingly short (see the "r. lacrimal"? The eye was behind that). What you're looking at is a modest snout attached to a greatly flaring right "cheek" (which comes with a scalloped fringe). Figure 1 in Brownstein (2022). CC BY 4.0.

Either way, the skull is worth a look. There's garden-variety "weird" and then there's "why is this all practically all post-orbital?" (It certainly wasn't for intellect, most of the posterior of choristodere skulls being a series of struts and bars. Note that the maxillary teeth of Kosmodraco only go back as far as the eyes.) Champsosaurus, as we've already seen, had a long, narrow toothy muzzle, with the rest of the skull being broad and low. Kosmodraco had a skull that was still low but much more wedge-shape in dorsal view, as if someone smooshed or amputated a Champsosaurus-like snout. The business end of a Kosmodraco skull is an interesting analog for the modern alligator gar. It's the back of the skull where things get different, as Brownstein (2022) notes. Kosmodraco has a lot more skull going on behind the eyes, which themselves are elevated on skull like those of an alligator. The posterior margin is also ornamented with a series of knobs, and the skull is quite low (Brownstein 2022).

A comparison of the palatal regions of choristoderes Kosmodraco and Champsosaurus to an alligator and an alligator gar also serves as a comparison of basic facial shapes for the four. Similarities between Kosmodraco and the gar aren't as great if you continue through the rest of the skull. Figure 13 in Brownstein (2022). CC BY 4.0.

I'd like to take the opportunity to note that there's another extinct group of aquatic tetrapods with flat, blunt, broad skulls and eyes relatively far forward on the skull, which has so far avoided comparisons to Simoedosaurus/Kosmodraco: the metoposaurid amphibians of the Triassic. Again, it's not a perfect comparison (metoposaur snouts are blunter), but it would seem to point to the long-term existence of a niche for freshwater predators with certain cranial adaptations.

One of the other points noted by Brownstein is there is more diversity in choristoderes than you might suspect by simply looking at the number of genera. For example, as of this writing Champsosaurus is composed of several species over about 20 million years. North American specimens have tended to be lumped with either the short-faced Simoedosaurus or the long-faced Champsosaurus.

References

Brownstein, C. D. 2022. High morphological disparity in a bizarre Paleocene fauna of predatory freshwater reptiles. BMC Ecology and Evolution 22: article number 34. doi:10.1186/s12862-022-01985-z.

Sunday, March 20, 2022

The Grand Pitch Formation

Back in October I posted on a formation I saw in Maine, the Matagamon Sandstone. While going through my photos, I realized I had a number of scenic and interesting shots of another formation, also not widely known: the Grand Pitch Formation.

Comes with waterfalls!

The Grand Pitch Formation goes back in the literature to the 1930s, when it was known as the Grand Falls Formation (Ruedemann and Smith 1935). This name, though, was already in use, so the more specific Grand Pitch name was substituted (Neuman 1962). The name refers to the Grand Pitch, a waterfall on the East Branch of the Penobscot supported by more resistant beds of the formation.

Resistant beds like these.

If you've taken a historical geology class in North America, you've probably spent some time with the assembly of eastern North America. Back when I was taking that class, it was a three-stage process marked by the Taconic, Acadian, and Alleghanian (or Appalachian) mountain-building events (orogenies). Well, as you might guess, it's a bit more complicated than that. (Just a bit.) In actual practice, the North American craton, microplates, continental fragments, island arcs, and all and sundry were bumping and jostling and colliding with each other all the time. In the present example, the Grand Pitch Formation was deposited not in North America, but on a Gondwanan terrane known as Ganderia (or Gander) that eventually piled up on the continent after a series of its own adventures (including running into another terrane) (Neuman and Max 1989).

Just like our slice of the Equator in Minnesota, here in Maine you can stand on a former sliver of the tropics.

The Grand Pitch Formation is a heterogeneous unit, including beds of gray, green, and red siltstone and slate, quartzite, and minor amounts of graywacke and tuff (Neuman 1967). Siltstone and slate are charming lithologies but are not noted for resistance to weathering; instead, the falls are supported by quartzite beds. The depositional environment has been interpreted as a continental slope-rise setting (Wellensiek et al. 1990).

Finer-grained beds as seen at the surface: not recommended for load-bearing outcrops.

It's a pretty thick formation, encompassing at least 1,500 m (5,000 ft) (Neuman 1967), but it's not in mint condition, to say the least. The formation has undergone several episodes of deformation, going back to the Ganderia days with a Cambrian–Ordovician event termed the Penobscot Orogeny or Disturbance (Neuman and Max 1989).

Red and gray beds make it easy to see minor faulting here.

The age of the Grand Pitch Formation is not entirely clear. Only one kind of fossil has ever been reported from it, the invertebrate trace fossil Oldhamia, which looks kind of like a fireworks burst or a palm frond and is thought to have been produced by something "mining" beneath microbial mats (Seilacher et al. 2005). Oldhamia was most abundant in the early Cambrian, but is not limited to that time frame, nor does its occasional presence mean the entire Grand Pitch Formation has to be that age, either (Neuman 1962, 1967). Generally the formation is attributed to some interval of the Cambrian.

Going back to deformations and alterations, here we have a patch of the formation scored with glacial striations.

References

Neuman, R. B. 1962. The Grand Pitch Formation: new name for the Grand Falls Formation (Cambrian?) in northeastern Maine. American Journal of Science, series 5, 260:794–797.

Neuman, R. B. 1967. Bedrock geology of the Shin Pond and Stacyville quadrangles, Penobscot County, Maine. U.S. Geological Survey, Washington, D.C. Professional Paper 524-I.

Neuman, R. B., and M. D. Max. 1989. Penobscottian-Grampian-Finnmarkian orogenies as indicators of terrane linkages. Pages 31–45 in R. D. Dallmeyer, editor. Terranes in the circum-Atlantic Paleozoic orogens. Geological Society of America, Boulder, Colorado. Special Paper 230.

Ruedemann, R., and E. S. C. Smith. 1935. The Ordovician in Maine. American Journal of Science, series 5, 30:353–355.

Seilacher, A., L. A. Buatois, and M. G. Mángano. 2005. Trace fossils in the Ediacaran–Cambrian transition: behavioral diversification, ecological turnover and environmental shift. Palaeogeography Palaeoclimatology Palaeoecology 227(4):323–356.

Wellensiek, M. R., B. A. van der Phijm, R. Van der Voo, and R. J. E. Johnson. 1990. Tectonic history of the Lunksoos composite terrane in the Maine Appalachians. Tectonics 9(4):719–734.

Sunday, February 13, 2022

Your Friends The Titanosaurs: Abditosaurus kuehnei

Today we add Abditosaurus kuehnei to the long-running "Your Friends The Titanosaurs" series. January was pretty slow around here as far as new non-avian dinosaurs go, but coincidentally enough the dinosaur to break the dry spell was a titanosaur. Since then, we've also gotten Guemesia ochoai, an abelisaurid, which is very nice if you enjoy theropods. (It did make entry #1600 in the dinosaur sheet of The Compact Thescelosaurus.)

Genus and Species: Abditosaurus kuehnei. "Abditus" is Latin for "concealed", referring to the long gap between discovery and description, making this a comrade of our friend Thescelosaurus neglectus. "Kuehnei" honors the discoverer, Walter Georg Kühne (Vila et al. 2022). Together we get something like "Walter Georg Kühne's concealed lizard".

Citation: Vila, B., A. Sellés, M. Moreno-Azanza, N. L. Razzolini, A. Gil-Delgado, J. Canudo, and A. Galobart. 2022. A titanosaurian sauropod with Gondwanan affinities in the latest Cretaceous of Europe. Nature Ecology & Evolution. doi:10.1038/s41559-021-01651-5.

Stratigraphy and Geography: The type and only known specimen comes from the lower Conques Formation at a locality identified as Orcau-1 (also known as "Barranco de Orcau" or "Orcau"). This location is about 6 km (4 mi) east of Tremp, in the county of Pallars Jussà, Catalonia, Spain (Vila et al. 2022).

Holotype: The holotype is not catalogued as a unitary specimen. Instead, the bones are held at the Museo Nacional de Ciencias Naturales in Madrid (MNCN) and the Museu de la Conca Dellà in Isona (MCD) and catalogued under a variety of numbers. The bones pertain to an associated and semi-articulated partial skeleton found over an area about 6 m by 4 m (20 ft by 13 ft) and include: isolated teeth, 12 partial articulated cervical vertebrae, 7 anterior and middle dorsals, cervical and dorsal ribs, 3 chevrons, the right and partial left scapula, right coracoid, left sternal plate, a sternal rib (a titanosaurian rarity), a fragment of the left ilium, parts of both humeri, partial right radius, part of the right femur, the right tibia and fibula, and partial left fibula with attached calcaneum (another titanosaurian rarity). Some other material has gone missing (Vila et al. 2022).

Abditosaurus kuehnei, as its name suggests, is one of those dinosaurs that was not described until decades after it had been discovered. The history of the specimen is described in the supplementary information to the paper (here; ten times longer than the paper, so yeah, necessary stuff!). The abridged Abditosaurus story is that Kühne discovered the fossils September 25, 1954 while prospecting for Cretaceous mammals. Over the next couple of weeks he collected a few bones and jacketed a few more for later collection. He made a return trip in 1955 and collected more bones. Plans for additional collection were scuppered by lack of funds. Lapparent and Aguirre (1956) proposed that Kühne's sauropod was a new species of Hypselosaurus, which is what you did in 1956. The locality was revisited in the mid-1980s, but not fully collected until a series of expeditions 2012–2014 (Vila et al. 2022 supplementary information).

A few anatomical notes: The humerus is notably robust while the tibia is gracile. The ilium is pneumatized. There are several osteological indications of age, such as the presence of a sternal rib and a calcaneum, thought to have only ossified with great age (Vila et al. 2022). (Also, the cervical ribs are fused to their vertebrae.) In the supplementary information Vila et al. describe osteological samples from the limb bones that indicate the type individual had reached skeletal senility (histological ontogenetic stage HOS-14). Vila et al. estimated that the sauropod was 17.5 m (57.4 ft) long and a shade more than 14 metric tons (15.4 US tons) in body mass. These figures would make A. kuehnei somewhat larger than a typical titanosaur, and definitely larger than your typical subcompact European titanosaur.

The size of A. kuehnei is one of the major talking points. Along with its lengthy history, this species comes equipped with a full suite of implications. While titanosaurs seem to be big fans of some kind of phylogenetic uncertainty principle, in this case A. kuehnei shows no indication of clading with other European titanosaurs. Instead, it hangs out in the general vicinity of saltasaurs and its phylogenetic best friend appears to be the even larger Paralititan stromeri from the Cenomanian of Egypt. Vila et al. (2022) posited a scenario in which North African titanosaurs arrived in Ibero-Amorica during an early Maastrichtian marine lowstand via a loop through the various smaller landmasses then dotting the narrow Tethys Ocean. They tied this to an early Maastrichtian faunal turnover in which the previous mini-titanosaurs were replaced, and suggested something similar happened in Romania. Let the fossil record show that large(ish) titanosaurs in the Haţeg Basin fauna of Romania have been reported by Le Loeuff (2005), Stein et al. (2010), and Mannion et al. (2019).

I've mentioned this before, but I suspect that sauropods were excellent at dispersal over water, similar to elephants. They were big, full of air and fermenting plant gases, and had long necks that could have been held well above the water. Get 'em out to sea, and they could probably have gone a long way. Postulate that your traveling sauropod was a gravid female, and given what we know about the number of eggs a sauropod could lay, you've got a pretty good scenario for populating any landmass that was large enough to support sauropods and a reasonable distance from a landmass that already had sauropods.

References

Lapparent, A. F., and E. Aguirre. 1956. Présence de dinosauriens dans le Crétacé supérieur du bassin de Tremp (province de Lérida, Espagne). Comptes Rendus Sommaires de la Société Geólogique de France 14:261–262.

Le Loeuff, J. 2005. Romanian Late Cretaceous dinosaurs: big dwarfs or small giants? Historical Biology 17:15–17.

Mannion, P., V. Díez Díaz, Z. Ciski-Sava, P. Upchurch, and A. Cuff. 2019. Dwarfs among giants: resolving the systematics of the titanosaurian sauropod dinosaurs from the latest Cretaceous of Romania. Journal of Vertebrate Paleontology, Program and Abstracts, 2019:148.

Stein, K., Z. Csiki, K. Curry Rogers, D. B. Weishampel, R. Redelstorff, J. L. Carballidoa, and P. M. Sandera. 2010. Small body size and extreme cortical bone remodeling indicate phyletic dwarfism in Magyarosaurus dacus (Sauropoda: Titanosauria). Proceedings of the National Academy of Sciences of the United States of America 107(20):9258–9263.

Vila, B., A. Sellés, M. Moreno-Azanza, N. L. Razzolini, A. Gil-Delgado, J. Canudo, and A. Galobart. 2022. A titanosaurian sauropod with Gondwanan affinities in the latest Cretaceous of Europe. Nature Ecology & Evolution. doi:10.1038/s41559-021-01651-5.