Suzhousaurus ("Suzhou lizard", named after the old name of Jiuquan, the city it was found in) is a genus of herbivorous therizinosauroid theropod dinosaur from the Early Cretaceous-age Xinminpu Group of the Yujingzi Basin, Gansu, China. The genus is known from two specimens discovered in the Xiagou Formation and the Zhonggou Formation, which are found in the Xinminbao Group. These findings were made during field work in 1999 and 2004. Although Suzhousaurus is known from these two specimens, a previously named and described therizinosauroid from the adjacent basin, "Nanshiungosaurus" bohlini , may be synonymous with the former. However, Suzhousaurus cannot be compared to this species due to non-overlapping material and material loss. Furthermore, this synonymy will result in Suzhousaurus bohlini with species "N". bohlini taking priority.
Suzhousaurus was an unusually large Early Cretaceous therizinosauroid that reached a length of 6 meters and almost 3.1 tons in weight. The upper arm was very different from that of therizinosaurids, causing Suzhousaurus to be considered a therizinosauroid. Unlike derived therizinosaurids, the vertebral column was not highly pneumatized, however, the pelvis shows a marked opisthopubic structure similar to that of therizinosaurids. Like other therizinosauroids, Suzhousaurus had elongated claws and neck for eating, robust hind legs, and a large trunk ending in a reduced tail.
With the description of the second, more complete specimen, the autapomorphies and validity of Suzhousaurus became clearer and with this, numerous anatomical features indicate that Suzhousaurus is a non-therizinosaurid therizinosauroid, therefore excluded from the derived Therizinosauridae. However, the genus is often recovered as the sister taxon of this family.
It is known from two partial postcranial skeletons,[1] including a distinctive upper arm that establishes it as a therizinosauroid. A study published in the journal Acta Geologica Sinica, found the animal's partial skeleton, which includes most of the back vertebrae, the shoulder, the front leg and part of the hips. Along with "Nanshiungosaurus" bohlini, which may be about the same age, Suzhousaurus was one of the largest known Early Cretaceous therizinosauroids.[2]
Suzhousaurus's closest known relative may be Nothronychus, fossils of which have only been found in somewhat younger rocks in New Mexico and Utah. This suggests that dinosaurs regularly traversed a transitory land bridge between North America and Asia early in the Cretaceous Period.
History of discovery[]
Diagram showing known remains from FRDC-GSJB-99 and FRDC-GSJB-2004-001
The holotype, FRDC-GSJB-99, was found in layers dating to the Aptian-Albian. It consists of a partial skeleton lacking the skull. It contains a distinctive right upper arm that establishes it as a therizinosauroid, a right scapula, ten dorsal vertebrae, ribs, a partial ilium and the pubis.[2] In 2008 another partial postcranial skeleton was described, specimen FRDC-GSJB-2004-001 found in 2004 at the same site. It contains the last three dorsal vertebrae, a sacrum of five vertebrae, the first six tail vertebrae, the left half of a pelvis and two thighbones.[3]
The type species Suzhousaurus megatherioides was named and described by Li Daqing, Peng Cuo, You Hailu, Matthew Lamanna, Jerrald Harris, Kenneth Lacovara and Zhang Jianping in 2007. The generic name is derived from Suzhou, the old name for Jiuquan, the prefecture the find was made in during the late twentieth century. The specific name indicates a resemblance to Megatherium, the giant ground sloth.[2]
Suzhousaurus might be identical to "Nanshiungosaurus" bohlini, an earlier named therizinosauroid found in the same formation and also known from limited remains. If so, the species name would be Suzhousaurus bohlini. A comparison is difficult because there is little overlapping material and the holotype of "Nanshiungosaurus" bohlini is lost.[2]
In 2008 a new and much more complete skeleton was described. The specimen FRDC-GSJB-2004-001 that contains the last three dorsal vertebrae, the sacrum composed of five sacral vertebrae, the first six caudal vertebrae, a very complete pelvic girdle composed of the left ilium, pubis and ischium, and both femurs, right femur is fragmented, it was discovered in 2004 by a field team from the Fossil Research and Development Center of Geology and Mineral Resources Exploration of Gansu Province, also in the Xinminbao Group. Since the left pubis of both specimens share similar features, these fossil remains represent another specimen for the taxon. Although both specimens lack cranial material, Button and colleagues reported an isolated dentary tooth referred to Suzhousaurus that was collected in the Yujingzi Basin. near the area of the two specimens, which was described in detail by the same team and You Hailu in 2017.
In 2018, You and colleagues proposed the Mazongshan fauna, which is composed of dinosaur taxa found in the Xiagou and Zhonggou formations, and provided more historical data of Suzhousaurus specimens , FRDC -GSJB-99 was discovered around 1999 and was found in the middle variegated gray beds of the Xiagou Formation dating to the early and mid Aptian and FRDC-GSJB-2004-001 was found in 2004 in the upper red beds of the Zhonggou Formation dating to the early Albian.
Description[]
Life restoration
Along with "Nanshiungosaurus" bohlini, which has the same age, Suzhousaurus was one of the largest known Early Cretaceous therizinosauroids,[2] with a length of 6 meters and a considerable weight of approximately 3.1 tons. In 2010 Gregory S. Paul estimated the body length at six metres, the weight at 1.3 tonnes.[4] Suzhousaurus is distinguished by a straight flat front part of the ilium and a flattened pubis curving strongly forward forming a hollow front edge of its shaft.[3] Suzhousaurus can be differentiated from all other therizinosauroid taxa by having a rounded upper edge of preacetabular projection of the ilium, a foramen in the obturator area with a total width greater than its height from top to bottom, a relatively short pubis with a deep and wide obturator notch, and the ischiadic axis is deviated posteriorly. Like other therizinosauroids, Suzhousaurus developed a prominent keratinous beak, had short, stout hind legs, a large belly, and a reduced tail. Feather impressions from the therizinosauroid Beipiaosaurus suggest at least partial feathering in Suzhousaurus.
The centers of the dorsal vertebrae in Suzhousaurus were mainly amphiplatelet, flat at both ends, and amphicoelous, strongly concave at both ends. In the most anterior vertebrae, large pleurocoelli, small air-filled holes, can be located on the lateral surfaces of the centrum, but these progressively decrease in size. Pneumatic openings are absent. Along with the centrum, the neural spines become more elongated in the posterior series. The neural spines are oriented subvertically on the anterior dorsals but slope more posteriorly. The neural canals, through which the spinal cord passes, are greatly reduced. The sacrum is composed of five well-fused vertebrae that show no signs of pneumatization. Its neural spines are a large plate. In general, the caudal vertebrae are smaller than the anterior vertebrae with more rounded facets. The width of the neural spine progressively decreases.
Schematic comparison of the ilium of Suzhousaurus (D) and other therizinosaurs
As a whole, the scapulocoracoid is a robust element that follows the shape of Segnosaurus and Therizinosaurus , but in a top view the scapular blade is highly curved, indicating a fairly round thorax. The right scapula is attached to the coracoid and both elements appear to be coossified as in most other therizinosauroids. The right humerus is a large element, measuring 550 millimeters long, however, it lacks several therizinosaurid features, the deltopectoral crest is more reduced than in most therizinosaurids such as Erliansaurus , Erlikosaurus , Neimongosaurus , Segnosaurus and Therizinosaurus , and the Posterior trochanter is not present on the posterior surface of the center of the humeral shaft, which is present in therizinosaurids. In addition, the lower end of the humerus is more flattened than in therizinosaurids. In these respects, Suzhousaurus is most similar to therizinosauroids such as Alxasaurus or Beipiaosaurus. . The pelvis has a strong opisthopubic condition. The ilium has an expanded and slightly curved anterior end and a long, rough structure can be located at the posterior end. Being strongly recurved and connected to the ischium, the pubis has a large pubic boot, great expansion at the lower end. The ischium has a widely expanded lower end similar to that of therizinosaurids. At its mid-height, a large crest-like structure articulates with the pubis. The femur is very thickened and robust, with a large trochanter and well-developed articular surfaces. It has a total length of 840 millimeters.
Classification[]
Li and coauthors, in their description of the genus, assigned Suzhousaurus to the Therizinosauroidea, in a basal position. They performed a cladistic analysis that found the genus to be more derived than Beipiaosaurus and Falcarius, less derived than Alxasaurus and true therizinosaurids, and the sister taxon of Nothronychus, forming a clade with it.[2] The more complete remains also confirm that Suzhousaurus It is more derived than Falcarius and Beipiaosaurus , and less derived than the therizinosaurids. In the large review of Therizinosauria by Lindsay Zanno in 2010, she found Suzhousaurus in a more derived position as the sister taxon of Therizinosauridae and representing the last divergent therizinosauroid. The latter has also been corroborated by Button and colleagues. In 2019, Hartman and his team performed a phylogenetic analysis for Therizinosauria using data provided by Zanno 2010 and found this time Suzhousaurus as a taxon of the therizinosaurids, however, with little support.
Relationships of Suzhousaurus and Falcarius. The former represents the latest diverging therizinosauroid
An analysis by Lindsay Zanno in 2010 found a more derived position as the sister taxon of the Therizinosauridae, as shown by this cladogram:[5]
| Therizinosauria |
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Paleoecology[]
The overall environmental deposition of the Xinminbao Group suggests a subsidence basin dominated by low-relief clastics in which weak, short-lived lakes repeatedly gave rise to open land biomes. Suzhousaurus was a relatively large herbivorous component of its ecosystems. The known specimens were recovered from the Mazongshan dinosaur fauna complex, which is composed of the contemporaneous genera of the Xiagou and Zhonggou formations. During the late Aptian and early Albian, a large lake surrounded by narrow hills was probably present in the Mazongshan and Jiuquan areas, allowing dinosaur faunas to travel across areas without geographical barriers.
Xiagou Formation[]
The vast majority of ornithothoracines are known from the near Changma Basin
The gray variegated beds in the Xiagou Formation of the Yujingzi Basin were deposited in lowland-like environments with coastal conditions. A great diversity of ornithothoracines is known from this formation, such as Avimaia , Changmaornis , Dunhuangia , Feitianius , Gansus , Jiuquanornis , Qiliania and Yumenornis . Other theropod dinosaurs known from the gray-variegated beds of Suzhousaurus include the large ornithomimosaur Beishanlong and the predatory tyrannosauroid Xiongguanlong . Additional herbivores are represented by Archaeoceratops , Jintasaurus , Qiaowanlong and Xuwulong.
Zhonggou Formation[]
The Albiend¡se Zhonggou Formation slightly overlies the sediments of the Xiagou Formation and consists of abundant red fluvial sedimentation. Apart from the aforementioned specimen of Suzhousaurus , scarce remains of Auroraceratops and Beishanlong are known from the red beds. The remains of ceratopsians and therizinosaurs in these beds could reflect a preference for niches close to rivers and lakes, while hadrosauroids and sauropods probably inhabited more interior environments in the region. However, remains of ceratopsians and therizinosaurs are also found in the gray-variegated beds of the Yujingzi Basin. In the Gongpoquan Basin, predominantly lacustrine conditions are represented by gray beds, which is consistent with a return to lacustrine deposits in the upper part of the Zhonggou Formation.
Appearance in other media[]
Jurassic Park[]
- Suzhousaurus was going to appear in Jurassic World: Primal Ops. However it was never added due to the game's closure in October 31st, 2022.
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Read more Suzhousaurus on Jurassic Park Wiki |
References[]
- ↑ Li, D., You, H., and Zhang, J. (2008). "A new specimen of Suzhousaurus megatherioides (Dinosauria: Therizinosauroidea) from the Early Cretaceous of northwestern China." Canadian Journal of Earth Sciences, 45(7): 769–779.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Template:Cite journal Cite error: Invalid
<ref>tag; name "Letal07" defined multiple times with different content - ↑ 3.0 3.1 Li, D., You, H., and Zhang, J. (2008). "A new specimen of Suzhousaurus megatherioides (Dinosauria: Therizinosauroidea) from the Early Cretaceous of northwestern China." Canadian Journal of Earth Sciences, 45(7): 769–779.
- ↑ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 158
- ↑ Template:Cite journal