Open Paleo

Manipulonyx

Averianov et al., 2025 man-IP-yoo-LOH-niks

From Latin 'manipulare' (to manipulate, to handle) and Greek 'onyx' (claw), referring to the specialized forelimb interpreted as a tool for handling eggs.

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Manipulonyx is an extinct genus of parvicursorine alvarezsaurid theropod from the Maastrichtian Nemegt Formation of the Hermiin Tsav locality, Govi-Altai Province, southern Mongolia. The single species, Manipulonyx reshetovi, is known from a fragmentary skeleton (PIN 3142/364) that preserves the most complete forelimb of any parvicursorine yet described, including the first documented complete set of proximal carpals (ulnare, intermedium, radiale) and a series of dermal carpal spikes (medial, lateral, and palmar) articulated with the carpometacarpus. Averianov, Lopatin and Atuchin (2025) interpret these spikes, together with the rudimentary third and fourth digits and the absence of a flexor tubercle on ungual II-2, as adaptations for gripping and piercing dinosaur eggs with the hypertrophied manual claw — a hypothesis supported by eggshell fragments associated with the holotype on its 1979 field label.

Diagnosis

  1. Internal tuberosity of humerus projects proximal to the humeral head, with no notch between humeral head and deltopectoral crest.
  2. Single distal condyle of humerus for articulation with both radius and ulna; ectepicondyle hypertrophied and projects distally.
  3. Olecranon process of ulna hypertrophied; manual digit 2 hypertrophied with very large and robust ungual phalanx bearing a large proximodorsal process on phalanx II-1.
  4. Ventral canals of manual phalanx II-2 closed laterally; manual digits 3 and 4 greatly reduced but present.
  5. Supraacetabular crest of ilium arcuate, not extending anteriorly beyond pubic peduncle; entocondylar tuber of femur present and directed posteriorly.
  6. Popliteal fossa of femur open distally; metatarsal 4 with lateral flexor ridge.

Species

Manipulonyx reshetovi Averianov et al., 2025

Type species

Honors Soviet paleontologist V. Yu. Reshetov, who discovered the holotype in 1979.

Holotype
PIN 3142/364 , Paleontological Institute, Russian Academy of Sciences
Material
Fragmentary skeleton including posterior cervical, first dorsal, sacral, and caudal vertebrae; scapulocoracoid; humeri; ulna; radius; carpals; complete manus; pelvis fragments; femur; tibia; metatarsals; and pedal phalanges.
Horizon
Nemegt Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Hermiin Tsav (northern outcrops), Govi-Altai, Mongolia

References

  1. Averianov, A. O.; Lopatin, A. V.; Atuchin, A. A. (2025). Forelimb structure and function in a new Late Cretaceous parvicursorine theropod dinosaur from Mongolia. Proceedings of the Zoological Institute of the Russian Academy of Sciences 329(4): 382-408. Zoological Institute, Russian Academy of Sciences. doi:10.31610/trudyzin/2025.329.4.382

    Erects Manipulonyx for PIN 3142/364; interprets the carpal dermal spikes and hypertrophied claw on manual digit II as adaptations for ovivory (egg predation).

    averianov2025a