| Tiamat valdecii | |
|---|---|
 | |
| Skeletal reconstruction | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Clade: | †Macronaria |
| Clade: | †Titanosauria |
| Genus: | †Tiamat Pereira et al., 2024 |
| Species: | †T. valdecii |
| Binomial name | |
| †Tiamat valdecii Pereira et al.,2024 | |
Tiamat (after theMesopotamian mythical goddess) is anextinct genus oftitanosaurian sauropod dinosaur from the 'mid'-CretaceousAçu Formation of Brazil. The genus contains asingle species,T. valdecii, known from severalcaudal vertebrae.
TheTiamatholotype specimen was discovered in sediments of theAçu Formation in thePotiguar Basin ofCeará state, Brazil. The specimen consists of nine fragmentarycaudal vertebrae from the beginning and middle of the tail, deposited in theFederal University of Rio de Janeiro.[1] An isolated titanosaurosteoderm described in 2018, specimen UFRJ-DG 549-R, was tentatively suggested to also have come fromTiamat.[2]
In 2024, Pereira et al.describedTiamat valdecii as a new genus and species ofbasaltitanosaur based on these fossil remains. Thegeneric name,Tiamat, referencesTiamat—the serpentine or draconic goddess ofSumerian andBabylonian mythology—who traditionally represents the mother of mythical beings, hinting at the basal phylogenetic position of the dinosaur. Thespecific name,valdecii, honors Dr. Valdeci dos Santos Júnior, the discoverer of thetype locality.[1]
Tiamat represents the first dinosaur to be named from the Potiguar Basin of Brazil, although the indeterminate remains of other dinosaurs have been found.[1]
In theirphylogenetic analyses, Pereira (2024) recoveredTiamat as abasal titanosaur, as thesister taxon to the similarly-agedAndesaurus. Their results are displayed in thecladogram below:
