Paleontology Newsflash: Analong chuanjieensis and Kholumolumo ellenbergerorum
Do you prefer the clarity of Chuanjiesaurus, or the warmer sound of Analong?
Analong is the skeleton on the right, in blue.
2020 has started off as the year of saurischia: all the new dinosaurs described and published this year have either belonged to theropoda or sauropodomorpha. April has added two more members of the sauropod line to the burgeoning list of dinosaur diversity. Since both papers remain behind pay walls for the moment and their details aren't generally accessible, I've decided to combine both findings into one Factoid.
Analong harks from Yunnan Province, Lufeng County, Chuanjie Township, near the village of Ana. That will be important later (YOU WILL BE QUIZZED ON THIS!!). This region has several sauropods and sauropod-like dinosaurs (sauropodomorphs) named after it: Yunnanosaurus, Lufengosaurus, and Chuanjiesaurus. Together with Analong, these taxa span the Early to Middle Jurassic epochs.
Scientists originally referred Analong chuanjieensis to a related dinosaur called Chuanjiesaurus anaensis. Further examination of this purported second specimen of Chuanjiesaurus led them to discover features of the skeleton they had overlooked before, which distinguish these two specimens as separate genera. Analong's full name translates as "The Dragon of Ana from Chuanjie," whereas Chuanjiesaurus' full name translates as "The Reptile of Chuanjie from Ana." See what they did there?
Both these sauropods come from the same quarry, so they probably lived at the same time and place. Both also belong to a predominantly Chinese group of dinosaurs called mamenchisaurids. Analong, however, more closely resembled the common ancestor of the group than other known members, while Chuanjiesaurus bones share more features with the geologically younger members of the group. Scientists term these conditions "basal" and "derived." To find a basal member of a group living alongside a derived one implies a complex evolutionary history. Considering that up until last year mamenchisaur fossils had only shown up in China, this suggested a degree of geographic isolation drove much of this diversification. The discovery of Wamweracaudia in Tanzania, Africa, puts a different spin on that story, though. The past couple of years have made mamenchisaurs much more interesting, and they were already pretty fascinating to begin with. They predate the diplodocids known from the Americas, like Brontosaurus, Apatosaurus, Supersaurus, Barosaurus, and of course Diplodocus, but they share a general body design with that group and may have lived similar lifestyles. They developed proportionally long necks to an absurd extreme: the nominal Mamenchisaurus' neck measured half the length of the entire animal! Apropos of a basal member of the group, Analong may have sported a more proportionally modest neck.
Other differences between Analong and its relatives include variations at the base of the tail, in its hips, its forearm, and its hand. Many of these differences show reduced or altered muscle attachment sites, suggesting variation in how this animal moved compared to its relatives. Chuanjiesaurus' neck was not preserved, so it would be difficult to test if this had anything to do with the length of the neck, but it might have.
Rocks that preserved these and other dinosaur species in the area all carry distinctive colors—reds, purples, oranges, and even greens—due to environmental conditions during the Middle Jurassic and chemical changes in the rocks since that time. The Dragon of Ana occurs in blood red rocks—make of that what you will (mwahaha). At least up until 2011, Analong was preserved in situ, just as it was found in 1995, where the World Dinosaur Valley museum was built around the quarry (much like the Cleveland-Lloyd or Douglas quarries in Utah). Along with the two mamenchisaurs, the quarry preserves the large theropod Shidaisaurus, other sauropod material, turtles, and other fossils.
Kholumolumo bones come from the Maphusteng bone bed in Lesotho, in southern Africa. It lived during the Late Triassic. Description for this species has been a long time coming: excavators recovered their bones between 1959 and 1970. They now reside at the Muséum National d’Histoire Naturelle in Paris, France.
Our knowledge of this species' skeleton derives from bones belonging to numerous individuals. Elements listed in the paper come from at least five as far as I can tell, and many more remain in the quarry. Known parts of the skeleton include two postorbital bones which form the back of the eye socket, representatives of most of the spinal column and tail, ribs, hips, limb elements
This dinosaur name joins a few others named in recent years and drawn from native African languages. Ngwevu and Mnyamawamtuka are also my favorites. The species name refers to members of the Ellenberger family who helped recover the bones.
Despite its size—estimated at 9 meters or 30 feet in length—the shape of Kholumolumo's limb elements show that it walked on two legs. A bipedal posture set the standard for sauropod relatives of the time, like the Massospondylus featured here at the Eccles Dinosaur Park.
Kholumolumo grew 50% longer than Massospondylus, though, and that is pretty impressive for a bipedal sauropodomorph.
Cladistic analyses place Kholumolumo at a more basal position than Massospondylus, with Sarahsaurus from Arizona and the recently discovered Xingxiulong from China as its closest relatives. Kholumolumo grew more than twice the length of its two phylogenetic cousins, which reached 3-4 meters (10-13 feet) and 4-5 meters (13-16 feet) respectively. That and the geographic distribution of these three taxa hint at an interesting dispersal history for this group, but more only more fossil discoveries can say for sure.
Ren, X. X., Sekiya, T., Wang, T., Yang, Z. W., & You, H. L. (2020). A revision of the referred specimen of Chuanjiesaurus anaensis Fang et al., 2000: a new early branching mamenchisaurid sauropod from the Middle Jurassic of China. Historical Biology, 1-16.
Sekiya, T. (2011). Re-examination of Chuanjiesaurus anaensis (Dinosauria: sauropoda) from the middle jurassic chuanjie formation, Lufeng County, Yunnan Province, southwest China. Memoir of the Fukui Prefectural Dinosaur Museum, 10, 1-54.
Mannion, P. D., Upchurch, P., Schwarz, D., & Wings, O. (2019). Taxonomic affinities of the putative titanosaurs from the Late Jurassic Tendaguru Formation of Tanzania: phylogenetic and biogeographic implications for eusauropod dinosaur evolution. Zoological Journal of the Linnean Society, 185(3), 784-909.
Peyre de Fabrègues, C., & Allain, R. (2020). Kholumolumo ellenbergerorum, gen. et sp. nov., a new early sauropodomorph from the lower Elliot Formation (Upper Triassic) of Maphutseng, Lesotho. Journal of Vertebrate Paleontology, e1732996.