Magnapaulia

Chapter • Meet the dinosaur

Overview

Magnapaulia laticaudus was one of the largest hadrosaurids — duck-billed dinosaurs — ever found. It had a bulky, heavily built body, powerful hind limbs, shorter but fully weight-bearing forelimbs, and a broad, flattened beak at the front of the skull. Behind the beak sat a dental battery of hundreds of tightly packed teeth that ground plant material to pulp. The species name laticaudus, 'broad-tailed', refers to its most distinctive feature: unusually tall neural spines above the tail vertebrae and deep chevrons below them gave the tail a strikingly deep, blade-like profile. The skull is only partly known, but the preserved pieces place Magnapaulia among the lambeosaurines, the hadrosaurid group whose members carried hollow head crests containing looping nasal passages. Like all hadrosaurids, Magnapaulia could switch between walking on all fours and rearing up on its hind legs. Quadrupedal walking was almost certainly the default for an animal of this mass, while bipedal movement may have been used for faster travel or for reaching higher browse. The tail was carried horizontally as a counterweight and never dragged on the ground; bundles of ossified tendons braced the spine like reinforcing rods. The hollow crests of lambeosaurines are today interpreted mainly as resonating chambers for calls and as visual display structures, which points to a socially active animal with a rich communication repertoire. The diet was entirely plant-based: conifer twigs, ferns, cycads and the flowering plants that were spreading rapidly through the Late Cretaceous. Teeth wore down constantly and were replaced throughout life, and a special hinge in the skull allowed the upper tooth rows to flex outward with each bite, producing a grinding motion. An animal this large must have processed enormous volumes of vegetation every day and would have shaped the plant communities around it. The fossils were collected during the 1960s and 1970s from the El Gallo Formation of Baja California, Mexico, in fieldwork led by William J. Morris. Morris described the material in 1981 as a new species of Lambeosaurus, L. laticaudus. In 2012 Albert Prieto-Márquez and colleagues reassessed the specimens in detail and concluded that the animal deserved its own genus, Magnapaulia, honouring Paul G. Haaga Jr., a long-standing supporter of natural history research in Los Angeles. Some specimens preserve skin impressions with small polygonal scales, giving an unusually direct look at the animal's body covering.

Chapter • Where it lived

Habitat

Magnapaulia lived roughly 74–72 million years ago, in the late Campanian stage near the end of the Cretaceous. Every confirmed specimen comes from the El Gallo Formation in the state of Baja California, northwestern Mexico — sediments deposited on a coastal lowland of river deltas, channels, floodplains and swampy backwaters close to the ancient Pacific shoreline. The climate was warm and humid with marked seasonality, and the vegetation included conifers, ferns, cycads and increasingly widespread flowering plants. At the time the region lay on the western side of the island continent of Laramidia.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy