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| Daurlong wangi Wang, Cau, Guo, Ma, Qing & Liu, 2022 |
Abstract
Dromaeosaurids were bird-like dinosaurs with a predatory ecology known to forage on fish, mammals and other dinosaurs. We describe Daurlong wangi gen. et sp. nov., a dromaeosaurid from the Lower Cretaceous Jehol Biota of Inner Mongolia, China. Exceptional preservation in this specimen includes a large bluish layer in the abdomen which represents one of the few occurrences of intestinal remnants among non-avian dinosaurs. Phylogenetically, Daurlong nests among a lineage of short-armed Jehol Biota species closer to eudromaeosaurs than microraptorines. The topographic correspondence between the exceptionally preserved intestine in the more stem-ward Scipionyx and the remnants in the more birdlike Daurlong provides a phylogenetic framework for inferring intestine tract extent in other theropods lacking fossilized visceral tissues. Gastrointestinal organization results conservative among faunivorous dinosaurs, with the evolution of a bird-like alimentary canal restricted to avialan theropods.
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| Daurlong wangi holotype. (a), whole specimen. (b), skull. (c), detail of orbit region. (d), feather remains associated to the thoracic vertebrae. (e), anuran skeleton. Scale bars: 20 mm (b), 10 mm (c). |
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| Diagnosis of Daurlong wangi. Specimen IMMNH-PV00731. Skull (a, b), left scapula (c), sternum and left hand (d, e), right forelimb (f). Reconstruction in (g) by M. Auditore (CC-BY 4.0). Combination of features diagnostic for D. wangi: 1, slender subnarial ramus of premaxilla extended caudally well beyond the external naris; 2, large, trapezoid promaxillary recess placed at the rostroventral corner of antorbital fossa; 3, maxillary fossa large, shallow and caudodorsally located, so that the pila promaxillaris is wider than the pila interfenestralis; 4, stepped subcutaneous surface of the ventral ramus of maxilla; 5, absence of pitted ventral ramus of the antorbital fossa; 6, robust fang-like maxillary teeth with straight to slightly convex distal crown margins; 7, distal end of first sternal rib fan-shaped. 8, bowed scapula; 9. radius and ulna more robust than any manual element; 10. wide overlap of the semilunate carpal over metacarpal II. In D, gray area indicates sternum, black areas indicate left hand elements. Abbreviations: af, antorbital fossa; de, dentary; ju, jugal; la, lacrimal; ma, maxilla; na, nasal; pm, premaxilla; su, surangular. Scale bar in G = 10 cm. |
Systematic palaeontology
Dinosauria
Theropoda
Dromaeosauridae
Daurlong wangi gen. et sp. nov.
Holotype IMMNH-PV00731, an almost complete dromaeosaurid (Figs. 1, 2, Supplementary information).
Locality and Horizon: Pigeon Hill, Morin Dawa Daur Autonomous Banner, Inner Mongolia Autonomous Region (N 48°39′40.76″/E 123°52′ 41.15″); Longjiang Formation, Lower Cretaceous.
Etymology: The genus name is derived from the Daur Nation, and the Chinese 龙 ("lóng") for "dragon". The species name honors Mr. Wang Junyou, director of the IMMNH.
Diagnosis: Mid-sized dromaeosaurid with (autapomorphies marked by asterisk): slender subnarial ramus of premaxilla extended caudally well beyond the external naris; large, trapezoid promaxillary recess placed at the rostroventral corner of antorbital fossa*; maxillary fossa large, shallow and caudodorsally located, so that the pila promaxillaris is wider than the pila interfenestralis*; stepped transition from the subcutaneous surface of maxillary ventral ramus to the antorbital fossa; fan-shaped distal end of first sternal rib*. Differential diagnosis: Daurlong further differs from Tianyuraptor because it bears longer and more robust maxillary teeth and a more robust ulna. Daurlong further differs from Zhenyuanlong because it lacks a pitted ventral ramus of the antorbital fossa, lacks markedly concave distal margins in maxillary tooth crowns, bears a bowed scapula, a more robust radius, and a wider overlap of the semilunate carpal over metacarpal II (Fig. 3).
Xuri Wang, Andrea Cau, Bin Guo, Feimin Ma, Gele Qing and Yichuan Liu. 2022. Intestinal Preservation in A Birdlike Dinosaur supports Conservatism in Digestive Canal Evolution Among Theropods. Scientific Reports. 12, 19965 DOI: 10.1038/s41598-022-24602-x
