Cedarosaurus weiskopfae is an Early Cretaceous sauropod from Utah, represented by a partial skeleton rather than by a complete animal. Its type preserves vertebrae, ribs, much of the shoulder and forelimbs, parts of the pelvis and portions of the hind limbs. The skull and neck are absent. These bones support a brachiosaurid placement, but a familiar long-necked silhouette still has to be completed using better-known relatives.
Quick facts
| Scientific name | Cedarosaurus weiskopfae Tidwell, Carpenter & Brooks, 1999 |
|---|---|
| Group | Sauropoda; Brachiosauridae in published analyses |
| Age | Early Cretaceous, Barremian–Aptian |
| Formation | Yellow Cat Member, Cedar Mountain Formation |
| Locality | Grand County, Utah, USA |
| Holotype | DMNH 39045, partial skeleton |
| Preserved anatomy | Dorsal and caudal vertebrae, ribs, shoulder, forelimb, pelvis and hind limb |
| Missing anatomy | Skull and cervical vertebrae |
A skeleton from the Yellow Cat Member
The holotype, DMNH 39045, came from the Yellow Cat Member of the Cedar Mountain Formation in Grand County, Utah. Virginia Tidwell, Kenneth Carpenter and William Brooks named the genus and species in 1999. The genus refers to the Cedar Mountain Formation; weiskopfae honours Carol Weiskopf, who contributed to field and laboratory work. The skeleton includes eight dorsal vertebrae, about 25 caudal vertebrae, ribs and chevrons, parts of both scapulae and coracoids, sternal plates, a right humerus, radius and ulna, a metacarpal, pelvic bones, femora, a tibia and foot elements.
The associated bones lay partly in anatomical order. Near the expected belly region, excavators found a pile of smooth stones interpreted as gastroliths. The position of the stones is directly observed; their use in digestion is an interpretation. The carcass appears to have remained partly intact while it was buried on a floodplain. Some exposed bone surfaces were eroded and trampled before additional sediment covered them. This history explains why parts of the skeleton are damaged without requiring a single catastrophic event.
What the limbs and vertebrae show
The forelimbs were relatively long, and the humerus approached the femur in length. Along with the robust limb bones, this is consistent with the elevated front end often seen in brachiosaurids. The metacarpals supported the front foot beneath the body, while the hind limbs carried substantial weight. The tail vertebrae and chevrons document a long muscular counterbalance. The animal was a quadruped, but these proportions do not give a precise walking speed or habitual neck angle.
Several details help distinguish the species, including a pronounced flange and a tubercle on the radius, and distinctive tubercles on the second metatarsal. The diagnostic case therefore depends on a combination of preserved bones. Since no cervical vertebrae are known, the elongated neck shown in artwork is reconstructed from other sauropods, not directly observed in Cedarosaurus.
Placement among sauropods
The 1999 description placed Cedarosaurus in Brachiosauridae. Michael D’Emic’s 2012–2013 revision of Early Cretaceous sauropods also recovered it as a brachiosaurid, distinguishing it from other regional taxa such as Sauroposeidon, which falls among somphospondylans in that analysis. These are results of comparative anatomy and phylogenetic analysis; future matrices may adjust the exact branching pattern.
A partial hind limb, FMNH PR 977, from the Paluxy Formation in Texas was referred to Cedarosaurus on the basis of foot characters. It is not physically connected to the Utah holotype and comes from a different formation. The referral is a reasoned taxonomic proposal, not proof that every similar Early Cretaceous sauropod foot belongs to this genus. Keeping it separate from the type helps avoid inflating the known anatomy without acknowledging the uncertainty.
Size, feeding and what remains unknown
Common reconstructions place the animal at roughly 15–20 metres long, but the range is broad because the neck, skull and parts of the tail are missing. These are comparative estimates, not measurements of a complete skeleton. No reliable mass follows from the known bones alone. As a sauropod, it was herbivorous, but the fossils do not identify its preferred plants or prove that its long forelimbs were used only to browse high vegetation. Teeth and gut contents are not preserved in the type.
The gastrolith interpretation suggests stones may have been swallowed, but it cannot establish exactly how food was processed. Nor do the bones demonstrate herding, nesting or skin colour. Compare Cedarosaurus with other long-necked dinosaurs in the dinosaur catalogue; its partial Utah skeleton preserves a very different evidence set from sauropods known chiefly through neck vertebrae.
Frequently asked questions
Is the Cedarosaurus skeleton complete?
No. DMNH 39045 preserves much of the trunk and limbs but lacks the skull, neck and many other elements.
Why is Cedarosaurus called a brachiosaurid?
The limb and vertebral characters were interpreted as brachiosaurid in the original description and in later phylogenetic analyses, including D’Emic’s revision.
Were the stones near the skeleton gastroliths?
They were found as a pile near the expected belly region and were interpreted as gastroliths. Their digestive role is plausible but not directly observed.
Does Cedarosaurus include fossils from Texas?
A partial Texas hind limb was referred to the genus based on foot anatomy, but it is separate from the Utah type and the assignment remains a referral rather than part of the holotype.