The last paratype leaf is from the species' northernmost location, having been recovered from an outcrop of the late early Miocene Skonun Formation on the northern side of Graham Island in the Haida Gwaii of British Columbia.
The paratype UBCB 2401 is in the University of British Columbia collections while the paratypes TMP P83.39.586 A,B and TMP P83.39.585 A,B are in the collections of the Royal Tyrrell Museum of Palaeontology in Alberta.
The holotype leaf is numbered number WWU-GK-020 and the paratype is number WWU-GK-008, both of which are currently preserved in the paleobotanical collections of Western Washington University in Bellingham, Washington.
Guaibasaurus was originally named on the basis of the holotype, MCN PV2355, a well-preserved partial postcranial skeleton and the paratype, MCN PV2356, an articulated and nearly complete left hindlimb, which were discovered in the "Sesmaria do Pinhal 2" locality near Candelária, Rio Grande do Sul, in Brazil, in the geopark of Paleorrota.
It is known from the holotype MNHN-SAL 1024, skull missing the apex of the rostrum and the paratype MNHN-SAL 3, second skull missing the apex of the rostrum, recovered from the Salla, Department of La Paz, Bolivia.
The paratype (USNM 885787), a juvenile specimen of 49 mm ML, was found in the stomach of a lancetfish (Alepisaurus ferox).
Six of the paratypes are in the same amber specimen as a spider, a mite, and a myrmicine ant, while the two juvenile paratypes are in a single amber also.
The species was first identified and named Sillago attenuata by McKay in 1985 from the holotype specimen collected in 1948 from Ras Tanura, Zaal Island in the Persian Gulf, with a number of paratypes also examined.
Zarafasaura is known from the holotype OCP-DEK/GE 315, an articulated incomplete dorsoventrally crushed skull and mandible and from the paratype OCP-DEK/GE 456, a complete mandible.