Open Paleo

Kryptops

Sereno & Brusatte, 2008 CRIP-tops Disputed

From Greek kryptos (covered/hidden) and ops (face); meaning "covered face", referring to the heavily textured surface of the maxilla

121.4–100.5 million years ago Aptian–Albian, Early Cretaceous
Early Cretaceous stages

Kryptops is an extinct genus of possibly chimeric abelisaurid theropod dinosaurs from the Early Cretaceous of Niger. It is known from a partial maxilla (upper jaw bone) found at the Gadoufaoua locality in the western Ténéré Desert, in rocks of the Aptian-Albian-age Elrhaz Formation. The fossils were collected in 2000 by a University of Chicago expedition to Niger led by American paleontologist Paul Sereno. They were then described in 2008 by Sereno and Steve Brusatte. The genus contains a single species, Kryptops palaios. Sereno and Brusatte referred several postcranial remains to Kryptops, but later studies have shown that these elements belong to an allosauroid theropod, leaving Kryptops to be only known from the incomplete maxilla.

Under dispute

Only the holotype maxilla is securely referable to Kryptops. Carrano and colleagues (2012) argued the associated postcranium is a chimera and referred it to a carcharodontosaurid, possibly Eocarcharia (though the postcranial elements do not overlap with the skull-only Eocarcharia holotype); later studies agree the postcrania are allosauroid. Delcourt (2018) questioned the genus's validity, noting the maxilla preserves only a single autapomorphy and may therefore be a nomen dubium. Other work treats the maxilla as a diagnosable abelisaurid and scores it alone in phylogenetic analyses (Farke and Sertich, 2013; Rauhut and Carrano, 2016; Cau and Paterna, 2025). Its position within Abelisauridae is unstable across analyses.

Diagnosis

  1. Deep secondary wall in anteroventral corner of antorbital fossa that completely obscures fossa with scalloped and fluted dorsal margin
  2. External texture on maxilla composed of short linear vascular grooves
  3. Narrow articular slot on maxilla for anteroventral process of nasal (primitive relative to other abelisaurids)

Species

Kryptops palaios Sereno & Brusatte, 2008 Disputed

Type species

From Ancient Greek 'palaios' meaning 'old', in reference to the ancient age of the fossils relative to other known members of the Abelisauridae.

Holotype
MNBH GAD1 , Musée National Boubou Hama
Material
Partial maxilla and initially associated postcranial elements; postcranials now regarded as allosauroid.
Horizon
Elrhaz Formation, Aptian–Albian, Early Cretaceous , 121.4–100.5 million years ago
Locality
Gadoufaoua, G88, Agadez, Niger

ICZN cases

References

  1. Sereno, P. C.; Brusatte, S. L. (2008). Basal Abelisaurid and Carcharodontosaurid Theropods from the Lower Cretaceous Elrhaz Formation of Niger. Acta Palaeontologica Polonica 53(1): 15-46. Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences). doi:10.4202/app.2008.0102 sereno2008a
  2. Carrano, M. T.; Benson, R. B. J.; Sampson, S. D. (2012). The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10(2): 211-300. Informa UK Limited. doi:10.1080/14772019.2011.630927

    Considered Kryptops palaios a chimera and referred the postcranium (notably the pelvis and sacrum) to a carcharodontosaurid, possibly Eocarcharia.

    carrano2012a
  3. Delcourt, R. (2018). Ceratosaur palaeobiology: new insights on evolution and ecology of the southern rulers. Scientific Reports 8(1). Springer Science and Business Media LLC. doi:10.1038/s41598-018-28154-x

    Questioned the validity of Kryptops, suggesting it may be a nomen dubium because the holotype maxilla preserves only a single autapomorphy.

    delcourt2018c
  4. Farke, A. A.; Sertich, J. J. W. (2013). An Abelisauroid Theropod Dinosaur from the Turonian of Madagascar. PLoS ONE 8(4): e62047. Public Library of Science (PLoS). doi:10.1371/journal.pone.0062047

    Scores Kryptops on the holotype maxilla alone, the only element undoubtedly abelisaurid, and agrees the postcranium is probably allosauroid.

    farke2013a
  5. Rauhut, O. W. M.; Carrano, M. T. (2016). The theropod dinosaur Elaphrosaurus bambergi Janensch, 1920, from the Late Jurassic of Tendaguru, Tanzania. Zoological Journal of the Linnean Society 178(3): 546-610. Oxford University Press (OUP). doi:10.1111/zoj.12425

    Codes Kryptops on the maxilla only, referring it to Abelisauridae on its rugose surface and reduced antorbital fossa, and treats the pelvic girdle as tetanuran.

    rauhut2016b
  6. International Commission on Zoological Nomenclature (2019). Notice of New Applications to the Commission (Cases 3788–3796). Bulletin of Zoological Nomenclature 76(1): 2. doi:10.21805/bzn.v76.a002

    Acknowledges receipt of Case 3795.

    iczn2019a
  7. International Commission on Zoological Nomenclature (2019). Closure of Cases (3773, 3795, 3811). Bulletin of Zoological Nomenclature 76(1): 165. doi:10.21805/bzn.v76.a051

    Closes Case 3795, recording that the case was not published.

    iczn2019b
  8. Cau, A.; Paterna, A. (2025). Beyond the Stromer's Riddle: the impact of lumping and splitting hypotheses on the systematics of the giant predatory dinosaurs from northern Africa. Italian Journal of Geosciences 144(2): 162-185. doi:10.3301/IJG.2025.10

    Finds the original hypodigm chimerical, an abelisaurid maxilla with allosauroid postcrania, and scores them as separate units.

    cau2025a