Your Friends The Titanosaurs, part 14: Kaijutitan, Karongasaurus, and Laplatasaurus

This time around there are two easy entries and one tougher entry. Kaijutitan maui was named this year, and Karongasaurus gittelmani seems to have been largely forgotten by researchers. On the other hand, Laplatasaurus araukanicus, one of von Huene's South American titanosaurs, is a (waste)basket case.

Kaijutitan maui

As of this writing (mid-July 2019), Kaijutitan maui is the most recently described titanosaur genus and species. It is known from a partial skeleton found in the Sierra Barrosa Formation at Cañadón Mistringa near Rincon de los Sauces in Neuquén Province, Argentina. This formation is also noted for the titanosaur Mendozasaurus, which should be coming up in a few months. The skeleton of K. maui was found in massive reddish mudstone, disarticulated but associated over about 20 square meters (24 square yards). It was described in Filippi et al. (2019).

The genus name incorporates the Japanese word "Kaiju", meaning "strange beast", and Greek "titan", while the species name is a nod to the acronym of the Museo Municipal Argentino Urquiza (MAU) at Rincon de los Sauces, where the type specimen is held (Filippo et al. 2019). This gives us something like "giant monster of the Museum Municipal Argentino Uriquiza". "Kaiju" being most famous as a descriptive term for Japanese monster movies and the giant monsters that inhabit them, it's a bit of a missed opportunity that it wasn't used for a titanosaur from Japan, but it certainly fits otherwise.

The holotype, MAU-Pv-CM-522, consists of nearly three dozen bones and bone complexes. They include a partial braincase, a couple of cervicals, cervical and dorsal ribs, a caudal, a partial left shoulder girdle with sternal plate, most of the long bones of the arms plus a couple of metacarpals, a possible ilium fragment, a tibia and incomplete femur, an astragalus, part of a metatarsal, and more fragmentary remains. Its most notable feature is a split cervical neural spine, which is fairly common among most sauropods but rare among titanosaurs (Filippo et al. 2019).

K. maui was among the larger titanosaurs, with the type specimen perhaps massing between 40 and 60 metric tons (44 to 66 US tons), although a narrower estimate cannot be made at this time due to the incompleteness of the specimen (Filippi et al. 2019). Other measurements were not included. Filippi et al. (2019) noted that it had a mix of basal and derived characteristics, unusual for a titanosaur of Coniacian age, and found it to fall out as a basal titanosaur, albeit with weak support.

Obviously, having only been published this year, there hasn't been a lot of time for K. maui to get into other publications. In fact, it's a bit of a surprise that it *has* turned up in another paper already: González-Riga et al. (2019), which itself is not quite published, included a paragraph of text at the end as a note added in proof, noting that K. maui appears to fall on the stout-limbed side of the titanosaur spectrum, comparable to Dreadnoughtus.

Karongasaurus gittelmani

Karongasaurus gittelmani has a minor claim to fame as potentially the first dinosaur named in a digital-only format. The genus name refers to the Karonga District of Malawi, and the species name honors Steve Gittelman, who had been the president of the Dinosaur Society. These give us "Steve Gittelman's Karonga District lizard". K. gittelmani is known from the aptly named Dinosaur Beds of the Mwakasyunguti area of the Karonga District in northern Malawi (Gomani 2005). The Dinosaur Beds date to the late Early Cretaceous and are so far best known for fossils of a different titanosaur, Malawisaurus dixeyi, which will be coming up probably in October. They also have a fairly typical assemblage of fishes, frogs, turtles, crocs (including the small and apparently burrowing Malawisuchus), and theropods (Jacobs et al. 1996).

K. gittelmani is based on Malawi Department of Antiquities (Mal)-175, a dentary, with a handful of isolated teeth assigned to the species. The dentary, 138 mm long (5.43 in), is curved such that if both halves were present, they would make a U shape rather than the squared-off jaw we've seen for some other titanosaurs (Antarctosaurus wichmannianus, Baalsaurus mansillai, Bonitasaura salgadoi, and Brasilotitan nemophagus). The teeth are up toward the anterior end of the dentary, but are not crowded together at the very front as in those square-jawed fellows. Mal-175 differs strongly from the dentary of Malawisaurus dixeyi, which has a much more acute "U", a much longer tooth row, and broader, flatter teeth. The type specimen and most of the teeth were found in a bone bed (CD-9) which otherwise yielded various remains of Malawisaurus dixeyi. A few caudal vertebrae, again mostly from CD-9, may also pertain to K. gittelmani; they definitely don't belong to M. dixeyi, but in the absence of confirmed Karongasaurus caudals we can't be certain that they belong to the other titanosaur, and in fact may pertain to two taxa (Gomani 2005).

Figure 28 from Gomani (2005), showing medial (A) and occlusal (dorsal) (B) views of the holotype dentary (40 mm scale), and teeth (C, D, and E; 20 mm scale). Full caption here. CC-BY-4.0, apparently.

K. gittelmani has not made a large number of appearances in the literature since its description. Sallam et al. (2018) and Gorscak and O'Connor (2019) included it in their phylogenetic analyses and found it to be a fairly basal titanosaur.

Because the holotype dentary of K. gittelmani was found during the time frame when nobody was quite sure what a titanosaur skull was supposed to look like, it was briefly thought to have come from a diplodocid (Jacobs et al. 1996). M. dixeyi itself was one of the first titanosaurs known from remains of the facial part of the skull, which in its case was short and blunt. The majority of titanosaur skulls studied since then have been elongate, but in the mid-1990s there was no way of knowing that titanosaurs in general weren't mostly like M. dixeyi, so it was perfectly natural to suspect that the long slender jaw with the pencil-like teeth came from a diplodocid.

Laplatasaurus araukanicus

Many titanosaur species are plagued by questionable specimen assignments and taxonomic decisions. Laplatasaurus araukanicus is right up there at the top of that heap. It was named in 1929 by Friedrich von Huene, but we have to go back a few decades prior to get at the beginning of the story, even though the fossils in question are no longer regarded as L. araukanicus. In fact, almost nothing ever considered to be Laplatasaurus araukanicus can be confidently placed in that species at this time.

We previously encountered an 1893 publication by Richard Lydekker when Argyrosaurus superbus was featured (speaking of species which became wastebins). Lydekker also named Titanosaurus australis in this publication, which may be more familiar to you as Neuquensaurus. Included in the T. australis fossils were a couple of dorsal centra, a femur, and a right humerus, which von Huene (1929a) concluded did not belong to T. australis (see Wilson and Upchurch 2003 and Gallina and Otero 2015 for specimen lists). He was right about the limb bones, at least, because Neuquensaurus limb bones are comically robust among titanosaurs, and the bones in question aren't. He then opted to place the non-T. australis bones into his new genus and species Laplatasaurus araukanicus, along with various other bones from several areas in Argentina (Huene 1929a). Shortly thereafter he added some odds and ends from Uruguay (Huene 1929b).* I will omit the tedious details concerning the various specimens, but the basic idea was that L. araukanicus was a larger and more gracile contemporary of T. australis (not that it's difficult for a sauropod to be larger and more gracile than "T. australis", but I digress).

*He followed this by transferring Lydekker's Titanosaurus madagascariensis to Laplatasaurus and assigning some bones from India to it (Huene and Matley 1933). He was on a roll.

At any rate, there was now a pile of bones labeled Laplatasaurus araukanicus, lacking any clear published evidence about their associations. For all anyone can tell 90 years later, von Huene was relying on an arcane intuitive sense once widespread among paleontologists, gradually lost over the years since then, which allowed the scientist to just know these things without having to explain. Unsurprisingly, later paleontologists have not been quite so confident in intuition (e.g., Bonaparte and Gasparini 1979, Powell 2003, Wilson and Upchurch 2003, Gallina and Otero 2015).

Von Huene also neglected to specify a holotype, which was remedied by Bonaparte and Gasparini (1979). They chose a gracile right tibia and fibula as the lectotype, a type specimen designated from an original type series: Museo de La Plata (MLP) 26-306, a.k.a. MLP C.S. 1128 for the tibia and 1127 for the fibula. The tibia is 640 mm long (25.2 in), and the fibula is 625 mm long (24.6 in). The material comes from the Anacleto Formation just west of Cinco Saltos (Gallina and Otero 2015). L. araukanicus being what it is, Wilson and Upchurch (2003) noted the possibility that even the lectotype tibia and fibula don't belong to the same individual. Be that as it may, it turns out (fortunately for L. araukanicus) that MLP 26-306 features a distinctive combination of features such as a "slender tibia with deep cnemial fossa", "fibula with extremely developed anterior fossa on the proximal end" and "fibula with a well-developed lateral tuberosity" (Gallina and Otero 2015). It's not the most informative species, but it's not completely hopeless, either. Gallina and Otero (2015) ran a phylogenetic analysis and found it to be most closely related to the Brazilian titanosaur Uberabatitan.

The lucky tibia and fibula MLP 26-306, found on Wikimedia Commons, illustrated by Gunnar Bevins (10 cm scale). CC-BY-4.0.

Powell (1986, 2003) concluded that L. araukanicus was a species of Titanosaurus. This has generally been rejected, Titanosaurus of course having problems of its own. It should be noted, though, that Powell also moved most of the specimens assigned by von Huene to L. araukanicus to Titanosaurus sp. Wilson and Upchurch (2003) tentatively considered L. araukanicus valid (and distinct from poor old Titanosaurus), but it fell to Gallina and Otero (2015) to do the heavy lifting toward rehabilitating the species. The end result was to remove everything from the species except the two lectotype bones. This leaves a lot of orphaned former L. araukanicus material lying around, not just von Huene's various specimens, but also specimens such as the titanosaur material from the Los Blanquitos Formation of Arroyo Morterito described by Powell (1979). Omitting those specimens that are missing or have been stolen, most can be attributed to Lithostrotia, but have not been found to be diagnostic beyond that, aside from the Rancho de Ávila material placed in cf. Bonitasaura sp. Other tibiae and fibulae among the collections lack the features of the lectotype, and can't be put into L. araukanicus. It's entirely plausible that some of the other specimens do belong to L. araukanicus, but to know for certain it will require the discovery of associated material that includes examples of the characteristic tibia and fibula.

Part of Plate 4 from Lydekker (1893). The humerus referred by von Huene to L. araukanicus is included on the left and right, and the femur is the central element. The shorter humerus was attributed to Microcoelus patagonicus, but is now assigned to Neuquensaurus (and you can see what I mean about its robustness).

References

Bonaparte, J. F., and Z. B. Gasparini. 1979. Los saurópodos de los grupos Neuquén y Chubut y sus relaciones cronológicas. Actas V Congreso Geológico Argentino, Neuquén 2:393–406.

Filippi, L. S., L. Salgado, and A. C. Garrido. 2019. A new giant basal titanosaur sauropod in the Upper Cretaceous (Coniacian) of the Neuquén Basin, Argentina. Cretaceous Research 100:61–81. doi:10.1016/j.cretres.2019.03.008.

Gallina, P. A., and A. Otero. 2015. Reassessment of Laplatasaurus araukanicus (Sauropoda: Titanosauria) from the Upper Cretaceous of Patagonia, Argentina. Ameghiniana 52:487–501. doi:10.5710/AMGH.08.06.2015.2911.

Gomani, E. M. 2005. Sauropod dinosaurs from the Early Cretaceous of Malawi, Africa. Palaeontologia Electronica 8.1.27A.

González Riga, B. J., M. C. Lamanna, A. Otero, L. D. Ortiz David, A. W. A. Kellner, and L. M. Ibiricu. 2019. An overview of the appendicular skeletal anatomy of South American titanosaurian sauropods, with definition of a newly recognized clade. Academia Brasileira de Ciências 91(Supp. 2): e20180374. doi:10.1590/0001-3765201920180374.

Gorscak, E., and P. M. O’Connor. 2019. A new African titanosaurian sauropod dinosaur from the middle Cretaceous Galula Formation (Mtuka Member), Rukwa Rift Basin, southwestern Tanzania. PLoS ONE 14(2):e0211412. doi:10.1371/journal.pone.0211412.

Huene, F. von. 1929a. Los Saurisquios y Ornitisquios del Cretáceo Argentino. Anales del Museo de La Plata 3:1–196.

Huene, F. Von. 1929b. Terrestrische Oberkreide in Uruguay. Centralblatt für Mineralogie, Geologie und Paläontologie Abteilung B 1929: 107–112.

Huene, F. von, and C. A. Matley. 1933. The Cretaceous Saurischia and Ornithischia of the central provinces of India. Palaeontologia Indica 21:1–74.

Jacobs, L. L., D. A. Winkler, and E. M. Gomani. 1996. Cretaceous dinosaurs of Africa: examples from Cameroon and Malawi. Memoirs of the Queensland Museum 39:595–610.

Lydekker, R. 1893. Contributions to the study of the fossil vertebrates of Argentina. I. The dinosaurs of Patagonia. Anales del Museo de la Plata, Seccion de Paleontologia 2:1–14.

Powell, J. E. 1979. Sobre una asociación de dinosaurios y otras evidencia de vertebrados del Cretácico Superior de la región de La Candelaria, Prov. de Salta, Argentina. Ameghiniana 1–2:191–
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Powell, J. E. 1986. Revision de los Titanosauridos de America del Sur. Dissertation. Universidad Nacional de Tucumán, Tucumán, Argentina.

Powell, J. E. 2003. Revision of South American titanosaurid dinosaurs: palaeobiological, palaeobiogeographical, and phylogenetic aspects. Records of the Queen Victoria Museum 111.

Sallam, H. M., E. Gorscak, P. M. O’Connor, I. A. El-Dawoudi, S. El-Sayed, S. Saber, M. A. Kora, J. J. W. Sertich, E. R. Seiffert, and M. C. Lamanna. 2018. New Egyptian sauropod reveals Late Cretaceous dinosaur dispersal between Europe and Africa. Nature Ecology & Evolution 2:445–451. doi:10.1038/s41559-017-0455-5.

Wilson, J. A., and P. Upchurch. 2003. A revision of Titanosaurus Lydekker (Dinosauria – Sauropoda), the first dinosaur genus with a "Gondwanan" distribution. Journal of Systematic Palaeontology 1(3):125–160.