Texas State Dinosaur: Paluxysaurus jonesi

The original 1997 designation of Pleurocoelus as Texas's state dinosaur seemed reasonable at the time. Pleurocoelus was a genus named by Othniel Charles Marsh in 1888 from Maryland material, and the name had been broadly applied to Early Cretaceous sauropod material from Texas for much of the twentieth century. The Texas sauropod bones — found in Hood County and nearby areas in the Twin Mountains Formation — were assigned to Pleurocoelus by default, because no better name was available.

The problem was that Pleurocoelus itself was based on fragmentary Maryland material (from the Arundel Formation), and the Texas material didn't necessarily belong to the same genus as the Maryland type specimens. The name was being used as a catch-all for Early Cretaceous American sauropod material that shared some similarities but might represent multiple distinct taxa.

When Peter Rose completed a detailed analysis of the Texas material in 2007 and published a formal description, he found that it had a distinct enough combination of features to warrant its own genus name. He named it Paluxysaurus jonesi — 'Jones's lizard of the Paluxy' — honoring both the river and the Jones Ranch where significant material had been found. Two years later, Texas updated its state dinosaur designation accordingly.

The Paluxy River runs through Glen Rose in Somervell County and Hood County, Texas. It is famous in paleontological circles — and increasingly in popular culture — for the dinosaur trackways exposed in its limestone bed and the adjacent banks. The tracks are Early Cretaceous in age, preserved in the Glen Rose Formation, and include both large three-toed theropod prints and the broad, rounded prints of large sauropods.

Dinosaur Valley State Park in Glen Rose preserves the most significant publicly accessible Early Cretaceous trackways in North America. The sauropod prints there — broad, rounded tracks from large animals — match what Paluxysaurus would have left: same time period, same river system, same animal type. Texas's state dinosaur is named for the river; the river's state park holds the footprints.

The sauropod tracks at Dinosaur Valley are generally attributed to large brachiosaur-type sauropods, and Paluxysaurus — as a large brachiosaurid-grade sauropod from the same time period and region — is a reasonable candidate for the trackmaker. This attribution is circumstantial: no direct skeletal association with the Glen Rose tracks exists, and other large sauropods may have been present. But the size and time period match, and Paluxysaurus's connection to the Paluxy region gives the state dinosaur a tangible geographic anchor.

The Jones Ranch bones in Hood County, the sauropod tracks at Glen Rose 40 miles south, and the theropod tracks attributed to Acrocanthosaurus at the same sites together sketch a coherent Early Cretaceous community — bones and footprints from the same world, preserved across two adjacent Texas counties. Few state dinosaur designations come with this kind of layered physical evidence still accessible in the ground.

Since Rose named Paluxysaurus in 2007, some researchers have proposed that Paluxysaurus and the related Oklahoma sauropod Sauroposeidon may represent the same animal — potentially making Paluxysaurus synonymous with the earlier-named Sauroposeidon. If this synonymy were formally accepted, Texas's state dinosaur name would need another update.

This question is not resolved. The anatomical comparison between Paluxysaurus and Sauroposeidon material is complicated by the fragmentary nature of both and the different elements preserved in each. Some analyses support synonymy; others maintain them as distinct. Texas's designation uses Paluxysaurus jonesi, which is the validly described species from Texas material regardless of how the Sauroposeidon question resolves. If the name changes in the literature in the future, another legislative update would be consistent with the pattern Texas has already established.