Amanzia greppini: a Swiss giant

We frequently associate Switzerland with chocolates, various types of cheese like Swiss cheese, and the Matterhorn mountain, not to mention that it hosts the headquarters of the United Nations and Red Cross. However, mainly lost in talk about Switzerland is the fact that fossils of dinosaurs and marine reptiles have been in Mesozoic deposits in Switzerland.

Right humerus NMB M.H. 260, left femur NMB M.H. 372, caudal vertebrae NMB M.H. 280 and NMB M.H. 255, and pedal ungual phalanx NMB M.H. 270, part of the syntype series of Amanzia greppini

The history of the discovery of Amanzia begins in the 1860s, when local workers found fossil reptile remains in a limestone quarry of the Late Jurassic (early Kimmeridgian) Reuchenette Formation in the Basse Motagne, near Moutier, Bern, northwestern Switzerland. Some of these fossils were sold to collectors, but others were placed in the collections of the Naturhistorisches Museum Basil (NHB) in Basel, Switzerland at the notice of geologist Jean-Baptiste Greppin. Because these remains were found in association with the holotype tooth of the indeterminate ceratosaurian theropod 'Megalosaurus meriani' (NHB M.B. 350), Greppin (1870) assumed that these remains were conspecific with 'M. meriani'. Postcranial reptile remains included in 'M. meriani' included: NMB M.H. 265 (cervical vertebra), NMB M.H. 266 (prezygapophysis of cervical vertebra), NMB M.H. 267–268 (cervical vertebrae), NMB M.H. 239 (caudal vertebra), NMB M.H. 245 (caudal vertebra), NMB M.H. 252–254 (caudal vertebrae), NMB M.H. 258 (caudal vertebra), NMB M.H. 271 (caudal vertebra), NMB M.H. 275–280 (caudal vertebrae), NMB M.H. 297 (caudal vertebra), NMB M.H. 324 (caudal vertebra), NMB M.H. 353–355 (caudal vertebrae), NMB M.H. 286 (caudal neural spine), NMB M.H. 300 (caudal neural spine), NMB M.H. 369–370 (caudal neural spines), NMB M.H. 291 (dorsal rib), NMB M.H. 306 (dorsal rib), NMB M.H. 344 (scapula), NMB M.H. 368 (scapula), NMB M.H. 284 (coracoid), NMB M.H. 260 (humerus), NMB M.H. 341 (humerus), NMB M.H. 259 (ulna), NMB M.H. 340 (ulna), NMB M.H. 264 (radius), NMB M.H. 346–347 (pubes), NMB M.H. 359 (pubis), NMB M.H. 358 (ischium), NMB M.H. 262 (femur), NMB M.H. 349 (femur), NMB M.H. 372 (femur), NMB M.H. 339 (tibia), NMB M.H. 342 (tibia), NMB M.H. 282 (fibula), NMB M.H. 373 (fibula), NMB M.H. 387 (fibula, ex NMB M.H. 374 and NMB M.H. 386), NMB M.H. 246 (metatarsal), NMB M.H. 269–270 (ungual phalanges), NMB M.H. 285 (long bone fragment), NMB M.H. 332 (bone fragment), NMB M.H. 345 (long bone fragment).  The quarry that yielded the remains of Amanzia greppini was in long-term use by the Swiss Army, and entry into the quarry was impossible until the late 1990s; at the current time of writing, the quarry near Moutier is now abandoned.

Friedrich von Huene (1875-1969), describer of Amanzia greppini

In the early 1920s, German paleontologist Werner Janensch examined the dinosaur remains unearthed at the Basse Motagne, and while he agreed that the 'Megalosaurus meriani' holotype was from a theropod (meriani was referred to the genus Labrosaurus [a junior synonym of Allosaurus] by Janensch [1920]), he noted that the postcranial remains associated with NHB M.B. 350 were actually referrable to Sauropoda. Based on this information from Janensch, von Huene (1922) described the sauropod remains as a new species of the Early Cretaceous macronarian genus Ornithopsis, O. greppini, the species name honoring the original describer of the sauropod material from the Reuchenette Formation. The syntype series of greppini constitutes as many as four individuals due to the presence of duplicate limb elements. Later, von Huene (1927) realized that O. greppini was generically distinct from the type species of Ornithopsis and referred it to the new eusauropod genus Cetiosauriscus, which is know only from the Middle Jurassic (Callovian) of southern England. Steel (1970) did not consider Cetiosauriscus to be a distinct genus from Cetiosaurus, and thus referred greppini to Cetiosaurus as Cetiosaurus greppini. McIntosh (1990), for his part, followed von Huene (1927) in referring the eusauropod material from the Reuchenette Formation to Cetiosauriscus. 

Skeletal restoration of Amanzia greppini with preserved elements in blue (from Schwarz et al. 2020)

Despite being significant as the most complete Jurassic dinosaur from Switzerland, "Ornithopsis" greppini itself received almost no attention in the literature until a review of dinosaur body and trace fossils from Switzerland was published by Meyer and Thüring (2003). They agreed with McIntosh (1990) that greppini is referable to Cetiosauriscus, noting that the two forms share anteroposteriorly short anterior caudal vertebrae and more elongate distal vertebrae, while pointing out that greppini differs from the Cetiosauriscus type species, C. stewarti, in having a more robust humerus whose shaft is proportionally more waisted anteriorly and with a more prominently developed deltopectoral crest. Schwarz et al. (2007a) described the preservation of cartilage in the syntypes of this taxon, and they later (2007b; see also Hofer 2005) indicated that "Ornithopsis" greppini constitutes a new genus of non-neosauropod eusauropod distinct from Cetiosauriscus based of preparation of "O." greppini syntypes by Antoine Heitz. A re-description of the taxon was finally published by Schwarz et al. (2020), who erected the new genus Amanzia for "O." greppini and phylogenetically recovered this taxon as a member of the eusauropod clade Turiasauria. The genus name was chosen to honor Amanz Gressly (1814-1865), who excavated the type material of the basal sauropodomorph Gresslyosaurus ingens in northern Switzerland in the late 1850s.

Although Amanzia was almost neglected by the paleontological community from the time of its initial description until the early 2000s, its journey from a referred specimen of a dubious theropod to being a sauropod, initially as a species of Ornithopsis, Cetiosauriscus, and Cetiosaurus before being finally recognized as a distinct genus in its own right is quite a superfluous one. Considering that the vast majority of sauropod taxa from Kimmeridgian-Tithonian marine deposits in Europe are known only from isolated elements, Amanzia, along with the dwarf macronarian Europasaurus from northwestern Germany, constitute the most complete Late Jurassic sauropods from central Europe. Who knows, one day a diplodocoid or a euhelopodid about as skeletally complete as Amanzia will be found in Late Jurassic marine deposits in western or central Europe.

References:

Greppin, J. P., 1870. Description géologique du Jura bernois et de quelques districts adjacents. Matériaux pour la carte géologique de la Suisse 8: 1–357.

Hofer, C., 2005. Osteologie und Taxonomie von Cetiosauriscus greppini (Huene 1927a, b) aus dem späten Jura von Moutier (Reuchenette Formation) [Osteology and taxonomy of Cetiosauriscus greppini (Huene 1927a, b) from the Late Jurassic of Moutier (Reuchenette Formation)]. Unpublished thesis, University of Basel. 70 pp.

Janensch, W., 1920. Ueber Elaphrosaurus bambergi und die Megalosaurier aus den Tendaguru-Schichten Deutsch-Ostafrikas. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1920: 225–235.

McIntosh, J. S., 1990. Sauropoda. pp. 345-401. In: D. B. Weishampel, P. Dodson, & H. Osmolska (eds.), The Dinosauria. Berkeley: University of California Press.

Meyer, C. A., and Thüring, B., 2003. Dinosaurs of Switzerland. Comptes Rendus Palevol 2: 103–117.

Schwarz, D., Wings, O., and Meyer, C. A., 2007a. Super sizing the giants: first cartilage preservation at a sauropod limb joint. Journal of the Geological Society 164: 61–65. 

Schwarz, D., Wings, O., & Meyer, C. A., 2007b. Taxonomische und systematische Revision von Cetiosauriscus greppini (Sauropoda). p. 147. In: O. Elicki & J. W. Schneider (Eds.). Fossile Ökosysteme (Vol. 36). Wissenschaftliche Mitteilungen, Institut für Geologie: Freiberg.

Schwarz, D., Mannion, P.D., Wings, O., and Meyer, C.A., 2020. Re-description of the sauropod dinosaur Amanzia (‘Ornithopsis/Cetiosauriscus’) greppini n. gen. and other vertebrate remains from the Kimmeridgian (Late Jurassic) Reuchenette Formation of Moutier, Switzerland. Swiss Journal of Geosciences 113: 2. https://doi.org/10.1186/s00015-020-00355-5

Steel, R., 1970. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology. Part 14. Saurischia. Stuttgart: Gustav-Fischer-Verlag.

von Huene, F., 1922. Ueber einen Sauropoden im obern Malm des Berner Jura. Eclogae Geologicae Helvetiae 17: 80–94.

von Huene, F., 1927. Short review of the present knowledge of the Sauropoda. Memoirs of the Queensland Museum 9: 121–126.

Are Qijianglong and Mamenchisaurus anyuensis of Middle Cretaceous age?

In a couple of scientific papers, Liu et al. (2017) and Wang et al. (2019) considered the Suining Formation (which overlies the Shangshaximiao Formation) to be of Aptian age based on U-Pb radiometric dating of detrital zircons from this unit, rather than Late Jurassic as stated by Dong et al. (1983) and Peng et al. (2005) based on tenuous biostratigraphic correlations. This conclusion potentially threw a wrench into the evolution of the eusauropod clade Mamenchisauridae, because the ages that Liu et al. (2017) and Wang et al. (2019) obtained for the Suining Formation indicated that mamenchisaurids survived until the middle Cretaceous. As the mamenchisaurid Qijianglong guokr and some referred specimens of Mamenchisaurus anyuensis are known from the Suining Formation (the holotype of M. anyuensis hails from the overlying Penglaizhen Formation), it occurred to me that any suggestion of the Penglaizhen and Suining Formations being much younger than the Shangshaximiao Formation once more reinforced the long-overdue need for a revision of Mamenchisaurus by implying that anyuensis would have to be assigned a new genus. In the meantime, however, Huang (2019) disputed the conclusion by Liu et al. (2017) regarding the age of the Suining Formation, arguing that the dating obtained from detrital zircons was affected by metamorphism and that the Suining Formation was not as young as concluded by Liu et al. (2017), asserting instead that the Suining Formation straddles the Tithonian-Berriasian boundary.

To begin addressing the question of whether or not Mamenchisaurus anyuensis and Qijianglong are of Middle Cretaceous age, it is imperative to analyze the available biostratigraphic evidence cited by Huang (2019) to make the case that the Suining and Penglaizhen Formations are older than asserted by Liu et al. (2017) and Wang et al. (2019) as well as state-of-the-art knowledge of mamenchisaurid evolution. Although Deng et al. (2015) and Wang & Gao (2012) date the Qigu Formation to 157-167 million years (late Callovian-early Oxfordian) based on U-Pb radiometric dating of detrital zircons from that unit, Huang (2019) asserts that the zircons used to determine this age estimate were likely recycled from the Xishanyao Formation, as volcanic rocks and tuffs have yet to be found in the Xishanyao Formation. As noted by Huang (2019), fossils of the ostracods Darwinula and Timiriasevia (which are of Late Jurassic age) appear in the lower parts of the Qigu and Suining Formations, whereas the Early Cretaceous ostracod Djungarica is present in the upper parts of the Qigu and Suining Formations but also the Penglaizhen Formation, indicating a latest Kimmeridgian-early Berriasian age for the Suining Formation and a late Berriasian-early Valanginian age for the Penglaizhen Formation. As Wang et al. (2019) admit, the traditional ages assigned to mamenchisaurid taxa from the Shangshaximiao, Suining, and Penglaizhen Formations by Dong (1980), Dong et al. (1983), and Peng et al. (2005) were based on tenuous stratigraphic correlations, and the age they assign to all Mamenchisaurus species from the Shangshaximiao Formation is largely consistent with the Oxfordian-Kimmeridgian age advocated for the Shangshaximiao by Huang (2019). Since the U-Pb radiometric dates obtained from detrital zircons from the Qigu and Suining Formations by Deng et al. (2015) and Wang et al. (2019) appear to have been subject to extraneous geologic factors like metamorphosis and recycling, it is highly reasonable to not rule out the possibly that the Suining and Penglaizhen Formations are of latest Kimmeridgian to Berriasian age rather than latest Aptian-Albian because the Cangxi Formation (located in the same basin as the Suining and Penglaizhen Formations) is of Berriasian-Valanginian age based on biostratigraphy (Hou et al. 2020).

At the current time of writing, an indeterminate cervical vertebra reported by Suteethorn et al. (2013) from the latest Tithonian-early Berriasian Phu Kradung Formation of northeastern Thailand is the only record of a mamenchisaurid from the Cretaceous, and if Wang et al. (2019) are correct, there would a be vast temporal gap between the Phu Kradung material and the mamenchisaurid taxa from the Suining and Penglaizhen Formations. No mamenchisaurid fossils have been found in the Valanginian-middle Aptian interval so far, even though basal eusauropod clade Turiasauria is present in Early Cretaceous deposits. Some of the fossils of Mamenchisaurus anyuensis have been found in the upper part of the Suining Formation, so the age of the Penglaizhen and upper Suining Formations would place M. anyuensis in the Berriasian-Valanginian interval. Since the youngest turiasaur fossils are from the Barremian-age Yellow Cat Member of the Cedar Mountain of Utah and the Cangxi Formation is slightly younger than the Penglaizhen Formation, a Berriasian-Valanginian or Hauterivan-Barremian age for Mamenchisaurus anyuensis and Qijianglong cannot be discounted, because no radiometric dates have been obtained for the Penglaizhen Formation.

Based on an analysis of the biostratigraphic evidence cited by Huang (2019) for the age of the Suning and Penglaizhen Formations as well as the age of geologic units underlying and overlying both the Suning and Penglaizhen Formations, along with prior knowledge of basal eusauropod evolution during the Early Cretaceous, it can be prudent to conclude that the Middle Cretaceous age proposed for Qijianglong and Mamenchisaurus anyuensis by Wang et al. (2019) is less likely than that concluded by Huang (2019) because of the age of the Qigu Formation and the presence of the earliest Cretaceous ostracod Djungarica in the upper Suining and Penglaizhen Formations. Even if Mamenchisaurus anyuensis and Qijianglong are not as young as proposed by Wang et al. (2019), the earliest Cretaceous age of these taxa doesn't diminish their significance, because they would still be younger than other nominal Mamenchisaurus species, and thus about the same age as the Phu Kradung mamenchisaurid, in which case Mamenchisaurus anyuensis would need a new generic name.

References:

Deng, S., Wang, S., Yang, Z., Lu, Y., Li, X., Hu, Q., An, C., Xi, D., and Wan, X., 2015. Comprehensive study of the Middle-Upper Jurassic strata in the Junggar Basin, Xinjiang (in Chinese). Acta Geosciences Sinica 36: 559–574.

Dong, Z.M. 1980. The dinosaurian faunas of China and their stratigraphic distribution. Journal of Stratigraphy 4: 256-263.

Dong, Z., Zhou, S. & Zhang, Y. 1983. Dinosaurs from the Jurassic of Sichuan. Palaeontologica Sinica 162: 1-151.

Hou, X.W., Shi, Z.J., Sun, Z.X., Tan, Z.Y., & Tian, X.S., 2020. The sporopollen assemblages in the Early Cretaceous red sediments in Cangxi area, northern Sichuan Basin and their geological significance. Geological Review 66 (3): 727-738. https://doi.org/10.16509/j.georeview.2020.0 3.014

Huang, D., 2019. Jurassic integrative stratigraphy and timescale of China. Science China Earth Sciences 62 223–255.

Liu G, Dong S, Chen X, Cui J. 2017. Detrital zircon U-Pb dating of Suining Fm. sandstone from the Daba Mountains, northeastern Sichuan and its stratigraphic implications. Palaeoworld 26: 380–395. 

Peng, G.Z., Ye, Y., Gao, Y.H., Shu, C.K. & Jiang, S. 2005. Jurassic Dinosaur Faunas in Zigong. People’s Publishing House of Sichuan, Chengdu, China.

Suteethorn, S., Le Loeuff, J., Buffetaut, E., Suteethorn, V., and Wongko, K. 2013. First evidence of a mamenchisaurid dinosaur from the Upper Jurassic–Lower Cretaceous Phu Kradung Formation of Thailand. Acta Palaeontologica Polonica 58 (3): 459–469.

Wang, J., Norell, M. A., Pei, R., Ye, Y. and Chang, S.-C., 2019. Surprisingly young age for the mamenchisaurid sauropods in South China. Cretaceous Research 104: 104176.