Norellraptor barsboldi: A new species of Microraptorine Dinosaur from the Early Cretaceous Jehol Biota of northeastern China.

The Microraptines are a small group of Paravian Dinosaurs (the group that includes Birds and their closest relatives, the Dromaeosaurs, Troodontids, and Scansoriopterygids), known mostly from the Early Cretaceous Jehol Biota of northeastern China. The remarkable preservation of the Jehol Biota fossils means that while the Microraptines were not apparently widespread or numerous, the specimens we do have are often exceptionally well preserved. Such fossils have produced Microraptines with feather-like integumentary structures, true pennaceous feathers and remnants of the gut contents, enabling a more detailed reconstruction of their ecology than has been possible for many more numerous Dinosaur groups.

Many Microraptines are interpreted as having been capable of flying, and the close relationship between Microraptines and Birds has made them an important group to palaeontologists studying the origin of flight. The closest sister group to the Microraptines is usually thought to be the Dromaeosaurs, a group of medium-sized Paravian Theropods clearly quite incapable of flight, which raises two possibilities. Either the ability to fly arose twice (or more than twice) within the Paravian clade, or the earliest members of the group had the ability, with groups such as the Dromaeosaurs losing this ability secondarily. 

In a paper published in the journal Nature Communications on 29 September 2026, Xuri Wang of the Key Laboratory of Stratigraphy and Paleontology of the Ministry of Natural Resources, and the Hebei GEO University, Yannan Ji of the Chinese Academy of Geological Sciences, Andrea Cau of the OPHIS Museo Paleontologico e Centro Erpetologico, Martin Kundrát of the Center for Integrative Paleobiology at Pavol Jozef Šafárik University, Yichuan Liu, also of the Key Laboratory of Stratigraphy and Paleontology of the Ministry of Natural Resources, and of the China University of Geosciences, Yang Wang, again of the Key Laboratory of Stratigraphy and Paleontology of the Ministry of Natural Resources, and Qiang Ji, also of the Hebei GEO University describe a new species of Microraptorine Dinosaur from the Early Cretaceous Jehol Biota of northeastern China.

The new species is named Norellraptor barsboldi, where 'Norellraptor' means 'Norell's Raptor' in honour of American palaeontologist Mark Allen Norell, and 'barsboldi' honours the late Mongolian palaeontologist Rinchen Barsbold (1957-2025), these being two scientists who have made exceptional contributions to the study of Paravian Dinosaurs. It is described from a single specimen (130108-MHGU-F4281) from an exposure of the Jiufotang Formation in the town of Lamadong, in Jianchang County, which is in western Liaoning Province.

Norellraptor barsboldi 130108-MHGU-F4281. (a) Whole specimen. (b) Skull in lateral view. (c) Close up of the rostrum. (d) Close up of the posterior part of skull. (e) Pectoral region. (f) Distal end of tail. Abbreviations: aof, antorbital fossa; arm, ascending ramus of maxilla; at, anterior tympanic recess; bt, basal tuber; bp, basypterygoid process; cf, coracoid fenestra; ct, caudal tympanic recess; cnV, 5th cranial nerve opening; cnVII, 7th cranial nerve opening; cv, cervical vertebra; d1, first dorsal vertebra; de, dentary; dt, dorsal tympanic recess; fo, foramen; fr, frontal; fu, furcula; gl, glenoid; h, humerus; la, lacrimal; lat, laterosphenoid; lcv, last caudal vertebra; lp, lateral pneumatic recess; mc, metacarpus; mxf, maxillary fenestra; na, nasal; oc, oto￾sphenoid crest; or, otic region; pa, parietal; paw, postantral wall; pmx, premaxilla; pp, paroccipital process; ppd, posterior processes of dentary; pt, pterygoid; pxf, promaxillary fenestra; r, radius; rp, retroarticular process; sa, surangular; sc, sca￾pula; so, supraoccipital; sp, sternal plate; sr, sclerotic ring; u, ulna; up, uncinate process; vor, ventral otic recess. Arrow indicates point of histological sampling. Scale bars are 50 mm (a); and 10 mm (b)–(f). Wang et al. (2026).

Norellraptor barsboldi has a skull triangular in lateral view, with an elongated snout, a vaulted area between the eyes, and very enlarged fenestra (skull openings). Its teeth are differentiated, with the premaxilary teeth being small and unserrated, while the maxilary teeth are larger, particularly so towards the back of the mouth, serrated, and hooked. Preserved plumage can be seen close to the right humerus and the synsacrum, ventral to the proximal caudal vertebrae, attached to the distal caudal vertebrae, ventral to the right tibiotarsus, and lateral to the right tarsometatarsus. However, the preservation of this is poor, preventing a detailed assessment of its structure.

Plumage of Norellraptor barsboldi (130108-MHGU-F4281). (a) whole specimen. (b) Distal tips of primary feathers. (c) Tibial plumage. (d) Distal tip of metatarsal feathers. (e) Plumage adjacent to humerus and thorax. (f) Plumage adjacent to ilium and tail base. (g) Distal tail feathers. Scale bars are 10 mm. Wang et al. (2026).

An osteological sample was taken from the distal portion of the mid-diaphysis of the left radius of specimen 130108-MHGU-F4281, and serial sectioned to give a view of its bone-structure. This section of bone had been crushed post-mortem, due to the weight of overlaying sediment. The bone is less than half a millimetre in diameter, and has a large medullary cavity lacking any internal structures, suggesting that the bone was heavily pneumatized in life. This is surrounded by a layer of laminated endosteal bone, making up 8-15% of the total bone thickness, then a thicker layer of periosteal bone, split into three layers by two lines of arrested growth (such lines typically form as an animal grows, with slowed growth in a season with less favourable conditions, such as winter or a dry season). This might be taken to mean the living Microraptor had lived at least two years after hatching. However, the large size of the inner cavity probably implies some total reabsorption of bone as the Dinosaur grew, making it several years older.

Histology of the left radius of 130108-MHGU-F4281. (a)–(c) Close-up of the left radius midshaft microstructure (d), (e). Physical transversal sections in transmitted (a), (d) fluorescent (b) and elliptically polarised light (c), (e). In (a)–(c) note an irregular interface between the inner periosteal bone and the endosteal bone (red arrow); a high difference in fluorescence between well-developed primary osteons of the zone 1 and of the inner group of osteons of the zone 2 (blue arrow); and ill￾developed primary of the outer group of osteons of the zone 2 (yellow arrow); a low fluorescence in the secondary osteonal bone (orange arrow). Compare the higher birefringence of the endosteal bone, an annulus-like tissue (white arrow), and early bone deposited to form zone 3 (black arrow). In (d), (e) note the occurrence of more organised osteocyte lacunae in the outer region of zone 1 and throughout the zone 2; increased birefringence in primary osteons of zone 1 (green arrow); in an annulus associate with Layer of Arrested Growth 1 (white arrow) and zone 3 (yellow arrow); and highly birefringent endosteal bone tissue (orange arrow). Abbreviations: ?ans, putative annulus; avbl, avascular layer; avr, avascular region; END, endosteal bone; FLB, fibro-lamellar bone; ICL, inner circumferential line; LAG, line of arrested growth; LAG-nvc, LAG crossing neurovascular canal; LAG1, inner circumferential layer; LAG2, outer line of arrested growth; ipos, ill developed primary osteon; lanvc, laminar neurovascular canal; lonvc, longitudinal neurovascular canal; meca, medullary cavity; onvc, neurovascular canal open on outer surface; osla, osteocyte lacuna; PER, periosteal bone; PFBM, parallel-fibered bone matrix; pos, primary osteon; pnvc, primary neurovascular canal; prpos, partially resorbed primary osteon; prsos, partially resorbed secondary osteon; ranvc, radial neurovascular canal; rel, resorption line; rupt, postfossilization rupture; snvc, secondary vascular canal; sos, secondary osteon; z1-3, first through third zone. Scale bars are 200 microns (a)-(c) and 100 microns (d), (e). Wang et al. (2026).

Norellraptor barsboldi shares many features with early Birds, but this appears to be a case of convergent evolution, with a phylogenetic reconstruction recovering it as a highly derived Microraptorine, and the Microraptors as the earliest branching group within the Paraves, i.e. the most distantly related group to the Birds within that larger group. This phylogeny shows the Microraptorines progressively acquiring 'Bird-like' traits over their history, apparently in response to similar evolutionary stimuli, something which Wang et al. interpret as evidence for the independent evolution of flight.

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