Wednesday, July 25, 2018

[Paleontology • 2018] Lingwulong shenqi • A New Middle Jurassic Diplodocoid Suggests An Earlier Dispersal and Diversification of Sauropod Dinosaurs


Lingwulong shenqi
Xu, Upchurch, Mannion, Barrett, Regalado-Fernandez, Mo, Ma & Liu, 2018


Abstract
The fragmentation of the supercontinent Pangaea has been suggested to have had a profound impact on Mesozoic terrestrial vertebrate distributions. One current paradigm is that geographic isolation produced an endemic biota in East Asia during the Jurassic, while simultaneously preventing diplodocoid sauropod dinosaurs and several other tetrapod groups from reaching this region. Here we report the discovery of the earliest diplodocoid, and the first from East Asia, to our knowledge, based on fossil material comprising multiple individuals and most parts of the skeleton of an early Middle Jurassic dicraeosaurid. The new discovery challenges conventional biogeographical ideas, and suggests that dispersal into East Asia occurred much earlier than expected. Moreover, the age of this new taxon indicates that many advanced sauropod lineages originated at least 15 million years earlier than previously realised, achieving a global distribution while Pangaea was still a coherent landmass.


Systematic paleontology
Sauropoda Marsh, 1878
Neosauropoda Bonaparte, 1986
Diplodocoidea (Marsh, 1884)

Dicraeosauridae Janensch, 1929

Lingwulong shenqi gen. et sp. nov.

Etymology: Lingwu, after the region where the specimens were found; long, the Mandarin Chinese for ‘dragon’; and shenqi, the Mandarin Chinese for ‘amazing’, reflecting the unexpected discovery of a dicraeosaurid in the Middle Jurassic of China.

Horizon and locality: Yanan Formation, late Early to early Middle Jurassic (late Toarcian–Bajocian), Lingwu Geopark, near Ciyaopu, Ningxia Hui Autonomous Region, China.

Diagnosis: Autapomorphies: prefrontal anterior process directed laterally; orbital dorsal margin strongly ornamented by deep, longitudinal grooves and tubercles; long-axes of the free tips of the basal tubera directed anteromedially; capitate process mediolaterally long (length:height ratio c. 5.0); occipital condyle articular surface wide transversely (width:height ratio c. 1.54); lateral surface of cervical prezygapophyseal process bears a ridge formed by a linear array of tubercles; subcircular facet-like region at the summit of metapophyses in middle cervical-anterior dorsal vertebrae; small process projects anterodorsally from the anterior margin of the transverse process, near its distal end, in anterior dorsal vertebrae; anterior dorsal metapophyses twisted along their length; anterior caudal neural spines bear subtriangular facet-like areas, extending from summit to spine mid-height.




Fig. 1 Cranial material of Lingwulong shenqi. Braincase in:
 left lateral (a), dorsal (b), occipital (c), and ventral (d) views. Dentary teeth in occlusal view (e). The 5th and 6th left dentary tooth crowns in labial view (f).

 Abbreviations: bpp, basipterygoid process; bt, basal tubera; f, frontal; fps, frontoparietal suture; gt, grooves and tubercles; pf, prefrontal; llp, ‘leaf’-like process; oc, occipital condyle; p, parietal; pcp, capitate process; paf, proatlantal facet; pag, proatlantal groove; pfap, prefrontal anterior process; po, postorbital; povp, postorbital ventral process; pp, paroccipital process; sc, sagittal crest; so, supraoccipital; sq, squamosal; sqhp, squamosal hook-like process; sqvp, squamosal ventral process; stf, supratemporal fenestra; wf, wear facet. Scale bars = 20 mm for a–e and 10 mm for f

Fig. 2 Skeletal reconstruction and exemplar skeletal remains of Lingwulong shenqi.
 Silhouette showing preserved elements (a); middle cervical vertebra in left lateral (b) and anterior (c) views; anterior dorsal vertebra in left lateral (d) and anterior (e) views; posterior dorsal vertebra in lateral view (f); sacrum and ilium in left lateral view (g); anterior caudal vertebra in left lateral (h) and anterior (i) views; right scapulocoracoid in lateral view (j); right humerus in anterior view (k); left pubis in lateral view (l); right ischium in lateral (m) views; right femur in posterior view (n); and right tibia in lateral view (o).

Abbreviations: ap, ambiens process; ar, acromial ridge; ip, iliac peduncle; naf, notch anterior to glenoid; np, neural spine; podl, postzygodiapophyseal lamina; ppr, prezygapophyseal process ridge; prp, prezygapophysis; pvf, posteroventral fossa; slf, shallow lateral fossa; spol, spinopostzygapophyseal lamina; sprl, spinoprezygapophyseal lamina; wls, wing-like structure. Scale bars = 100 cm for a and 5 cm for b–o

Fig. 3 Time-calibrated evolutionary tree for Eusauropoda. Agreement subtree produced in TNT, with additional diplodocid taxa incorporated (see Supplementary Note 4). All macronarian taxa have been combined into a single lineage, and non-sauropod sauropodomorphs have been removed, in order to enhance clarity (see Supplementary Fig. 13 for the full version of this tree). Silhouettes of dinosaurs drawn by Scott Hartman, Mike Taylor, and Mathew Wedel, and available at Phylopic (phylopic.org) under a Creative Commons Attribution 3.0 Unported license. Global paleogeographic reconstructions from the Paleobiology Database (paleobiodb.org)
  


Xing Xu, Paul Upchurch, Philip D. Mannion, Paul M. Barrett, Omar R. Regalado-Fernandez, Jinyou Mo, Jinfu Ma and Hongan Liu. 2018. A New Middle Jurassic Diplodocoid Suggests An Earlier Dispersal and Diversification of Sauropod Dinosaurs. Nature Communications. 9, 2700.  DOI:  10.1038/s41467-018-05128-1

'Amazing Dragon' Fossil Upends Origins of World's Largest Dinosaurs on.natgeo.com/2JQPINr @NatGeoScience

   

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