Genus: Secernosaurus BRETT-SURMAN, 1979
Etymology: Latin, secerno, “sever of divide”, referring to its non-Laurisian origin, and Greek, sauros, “lizard”: “Separated lizard”.

Species: koerneri BRETT-SURMAN, 1979
Etymology: In honor of Dr. Harold E. Koerner, professor emeritus, University of Colorado.

Holotype: FMNH P13423

Locality: 2 miles east of head of Rio Chico, near the Lake Colhue Huapi and to the west of the Gulf of San Jorge, Chubut Province, Patagonia, Argentina.

Horizon: Upper Bajo Barreal Formation (old San Jorge Formation, (?Laguna Palacios Formation, BONAPARTE, 1996)).

Biostratigraphy:

Age: Maastrichtian Stage, Upper Senonian Subepoch, Upper Gulf Epoch, Late Cretaceous.

Material: Ilia, prepubis, scapula, fibula, caudals, and partial braincase.

Referred material:

= Kritosaurus australis BONAPARTE, FRANCHI, J. POWELL & SEPULVEDA, 1984
Etymology: Latin, australis, "south." In reference to South America.
= Kritosaurus australis BONAPARTE, 1984 (nomen nudum)

Holotype: MACN-RN 02

Locality: Near the Arroyo Verde, southeastern Rio Negro Province, (Central Investigaciones Cientificas de Rio Negro Province), near the border of Chubut Province, Patagonia, Argentina.

Horizon: Los Alamitos Formation.

Biostratigraphy:

Age: Allenian Tetrapoda Assemblage, Late Campanian-Early Maastrichtian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.

Material: Occipital region of the skull, several cervical, dorsal, sacral and caudal vertebrae, pelvis and pectoral girdle, femur and several fragments of appendicular bones.

Referred material:

MACN-RN 142 "exemplar A": Incomplete skull, and jaw, several vertebrae and scapula.

MACN-RN 143 "exemplar B": Braincase and sphenoid region.

MACN-RN 144: Fragmentary skull with the frontal region and its ventral projection rather well preserved, and the incomplete temporal and occipital region.

MACN-RN 145: 11 dorsal and 6 caudal vertebrae, radius, ulna, distal fragment of femur with closed intercondylar canal, 2 metatarsi, ribs and a predentary fragment with well developed denticles.

MACN-RN 146: Several vertebrae, and almost complete ilium and portion of the other, fragment of an ischium, a scapula and ribs.

PREITO-MARQUEZ & SALINAS, 2010

MACN-RN 826: Right sternal, proximal half of a right scapula, left ilium lacking the pubic and ischial peduncles, and various cervical and anterior and middle dorsal vertebrae.

MACN-RN 987: Articulated series of distla caudal vertebrae.

MACN-RN 990: Pedal phalange III1.

MACN-RN 991: Fragment of left squamosal, fragment of right surangular.

MACN-RN 997: Right tibia.

MACN-RN 998: Right dentary (heavily reconstructed with plaster).