Patagosaurus is from Patagonia and is one of the sauropods most closely related to Periasaurus. Credit: Paul et al. (2020)
A medium-sized sauropod dinosaur inhabited the tropical lowland forest zone of the Serranía del Perijá in northern Colombia approximately 175 million years ago, according to a new study by an international team of researchers published in Journal of Vertebrate Paleontology.
The new species is a long-necked, plant-eating dinosaur known from a single trunk vertebra that is about half a meter tall and wide. The vertebra bears a distinct pattern of bony spurs that identify it as the new dinosaur species Perijasaurus lapaz (pear-EE-hah-SOW-roos la-PAHZ) — named in recognition of the mountainous region where it was discovered and the 2016 peace d. contract that allowed scientists to continue their research decades after the discovery of the fossils in 1943.
Perijasaurus is the northernmost occurrence of a sauropod in South America and represents an early phase in their evolutionary history.
“This new genus and species in the Paleotropics allows us to understand a little more about the origin of sauropods in the Jurassic period, as well as how they gave rise to later Cretaceous sauropods,” said lead study author Aldo Rincón Burbano, professor in Physics and Geosciences at the Universidad del Norte in Colombia.
The fossil was first discovered in 1943 during a geological mapping campaign by the Tropical Oil Company. The specimen was deposited in the collections of the University of California, Berkeley and was tentatively described in 1955.
University of Michigan curator and paleontology professor Jeff Wilson Mantilla studied the specimen as an undergraduate in 1997 and later developed a Fulbright-supported project to study the early evolution of sauropods in Colombia.
As part of this project, the Columbian specimen was loaned to UM, where chief preparator William Sanders removed the adhesives and plaster, greatly increasing the visibility of anatomical detail and reducing the overall weight of the specimen.
“After re-dissecting the fossil, we were able to better visualize the delicate bony laminae that connect the protruding parts of the vertebrae—the spine, the intervertebral joints, the rib joints—the architecture of these connections provides critical morphological information that identifies it as a new species and places in the sauropod family tree,” said Wilson Mantilla.
A 3D model of the specimen is hosted at the University of Michigan’s Online Fossil Repository.
A 1964 conflict between the Colombian military, the FARC guerrilla group, and paramilitary groups made it unsafe to conduct research in the Serranía del Perijá, near the Colombian-Venezuelan border, until the 2016 peace accords.
Since then, the research team has been working to determine with greater precision where the fossil was found. A satellite image of the region was overlaid on a 1955 hand-drawn map showing the location of the fossil. An additional clue was provided by sediment removed from the vertebra itself during the preparation process, allowing the team to determine the specific layer from which the bone was collected. Fieldwork at the site and neighboring localities helped to reconstruct the paleoenvironment inhabited by the dinosaurs.
“Periasaurus lived in a low-slope environment associated with a river and forested area. We found fine sand and leaf debris in the sediment deposited in the area where the vertebra was originally found, and it corresponds to the sediment in the neural arch of the vertebra, which are only preserved near a floodplain, ie. near the slopes of a river, a wooded area,” said Daniel Raad, a former geology student at the Universidad del Norte.
Most of the dinosaur discoveries in South America come from Cretaceous rocks located in Argentina and Brazil. Dinosaurs from northern South America were much rarer, especially during the Jurassic and Triassic periods, during the initial radiation of dinosaurs, when the land masses were still significantly interconnected.
“Although Perijasaurus is represented by a single vertebra, this area of the skeleton provides the most information in sauropods, due to a series of laminae and other structures,” said Martin Escura, paleontologist and associate researcher of CONICET (Argentina’s National Council for Scientific and Technical research) and Chief Curator of Paleoinvertebrates at the Argentine Museum of Natural Sciences.
The researchers were able to determine the evolutionary relationships of Perijasaurus through a computational analysis focused on early and middle Jurassic sauropods.
One trunk vertebra, which is about half a meter tall and wide, allowed scientists to identify a new species of long-necked, plant-eating dinosaur. Credit: UM Online Repository of Fossils viewer developed by the UM Museum of Paleontology
“Periasaurus was part of an early radiation of sauropods that included species from southern South America, Africa, Asia and Europe,” said Harold Jiménez Velandía, a geologist at the University of Caldas.
The presence of Perijasaurus in the paleotropics of South America, together with its close phylogenetic relationship to geographically widespread low-latitude species, suggests that sauropods diversified and dispersed relatively rapidly after a major anoxic event at the end of the Lower Jurassic, when parts of the oceans were depleted of oxygen over large geographic areas.
“What we see in the early Jurassic, both at high latitudes and in the most tropical regions, is that sauropod species were evolutionarily and geographically interconnected, something that is also seen in other groups of carnivorous and herbivorous dinosaurs.” “, said Escura.
Sauropods are the largest animals to have walked on land, with some reaching an estimated length of 49 meters and weighing up to 57 metric tons. Their ability to support their weight and move their bodies efficiently stems from a series of adaptations to reduce weight and increase bone support.
An anatomical hallmark of sauropods is vertebral pneumaticity. Essentially, extensions of the air sac system of the lungs extend into the spine and actually remove the internal bone, effectively lightening the skeleton.
“By the Late Jurassic, sauropods had evolved highly pneumatic vertebrae, perforated with air spaces that removed half to three-quarters of the bone weight. “Perijasaurus represents an evolutionary ancestor in which pneumatic intrusions were much simpler and more limited in extent, removing little more than a quarter of the bone volume,” Wilson Mantilla said.
He said the team will continue to focus on regions of Colombia that have exposures of Jurassic sediments.
“Colombia is emerging as a country with great potential to contribute to the paleontology of the continent and the world,” said Wilson Mantilla.
Perijasaurus is permanently housed at the University of California Museum of Paleontology in Berkeley, California.
Three fossils shed light on dinosaurs in China More information: Aldo F. Rincón et al, A sauropod from the Lower Jurassic La Quinta Formation (Dept. Cesar, Colombia) and the initial diversification of eusauropods at low latitudes, Journal of Vertebrate Paleontology (2022). DOI: 10.1080/02724634.2021.2077112
Specimin 3D model: umorf.ummp.lsa.umich.edu/wp/wp … e=1673&extension=ctm
Courtesy of the University of Michigan
Citation: New long-necked dinosaur helps rewrite evolutionary history of South American sauropods (2022, August 10) Retrieved August 10, 2022, from
This document is subject to copyright. Except for any fair dealing for the purposes of private study or research, no part may be reproduced without written permission. The content is provided for information…
Add Comment