Taxonomists S.A. Forbes and R. E. Richardson classified the pallid sturgeon in 1905, grouping it in the Scaphirhynchus genus and the Acipenseridae family, which includes all sturgeon worldwide. The pallid sturgeon’s closest relatives are the shovelnose sturgeon (Scaphirhynchus platorhynchus), which is still relatively common, and the critically endangered Alabama sturgeon (Scaphirhynchus suttkusi), which may soon become extinct. These three species belong to the Scaphirhynchinae subfamily, which has only one other genus, Pseudoscaphirhynchus, represented by three species found in west-central Asia.
Pallid sturgeon (Scaphirhynchus albus), as well as other sturgeon species, are often referred to as “living dinosaurs.” Sturgeon believed to be precursors to or possibly common ancestors of contemporary Scaphirhynchus species coexisted with dinosaurs during the Cretaceous period of the Mesozoic era. Evidence for this coexistence is based on North American fossil sturgeon specimens (Priscosturion longipinnis and Protoscaphirhynchus squamosus) which date up to 78 million years before present (Grande and Hilton 2006; Hilton and Grande 2006; Grande and Hilton 2009). Today, eight species and one subspecies of sturgeon in North America belong to the family Acipenseridae; specifically these are:
- Pallid sturgeon (Scaphirhynchus albus) – E;
- Shovelnose sturgeon (Scaphirhynchus platorynchus);
- Alabama sturgeon (Scaphirhynchus suttkusi) – E;
- White sturgeon (Acipenser transmontanus) – E;
- Green sturgeon (Acipenser medirostris) – T;
- Lake sturgeon (Acipenser fulvescens);
- Shortnose sturgeon (Acipenser brevirostrum) – E;
- Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus);
- Gulf sturgeon (Acipenser oxyrinchus desotoi) – T;
Six of these species are on the Federal list of endangered and threatened wildlife and plants, of which two species are listed as threatened (T) and four are listed as endangered (E).
The Pallid sturgeon was listed as endangered on September 6, 1990 (55 FR 36641-36647).