Fish
Xiphactinus audax
Bulldog fish
Xiphactinus audax is the giant predatory fish of the Niobrara Chalk, famous for the 'fish-within-a-fish' specimen at Hays, Kansas. Collectors hold its large fang-like teeth, vertebrae and fin rays from the Smoky Hill Chalk; complete skeletons are museum objects. Its teeth are round in cross-section and unserrated.
| Phylum | Chordata |
|---|---|
| Class | Actinopterygii |
| Order | Ichthyodectiformes |
| Family | Ichthyodectidae |
| Group | Fish |
| Size | to 5–6 m |
| Rank (PBDB) | genus· Paleobiology Database |
| Author | Leidy 1870· Paleobiology Database |
| Classification (PBDB) | Chordata › Osteichthyes › Ichthyodectiformes › Ichthyodectidae· Paleobiology Database |
| Range (PBDB) | 121–66 Ma· Paleobiology Database |
| PBDB occurrences | 59· Paleobiology Database |
Photographs
Elsewhere
- GBIF: 9327863
- PBDB: 35308
- Wikidata: Q55518957
- PBDB taxon page
- Wikipedia: Xiphactinus audax
- PBDB search: Xiphactinus
Cite this article
Stratum Strata. "Xiphactinus audax" (Taxon). Stratum Strata pack 2026.09, as of 2026-09-21. https://stratum.black/strata/taxa/xiphactinus-audax. Accessed 2026-09-21.
@misc{stratum-xiphactinus-audax,
title = {Xiphactinus audax},
author = {{Stratum Strata}},
howpublished = {\url{https://stratum.black/strata/taxa/xiphactinus-audax}},
year = {2026},
note = {Taxon article, Stratum Strata pack 2026.09, as of 2026-09-21; sources: stratum, pbdb, wikidata, smithsonian, nhm. Accessed 2026-09-21.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.