The largest fossil rodent

Area of Science:

• Paleontology
• Vertebrate Zoology
• South American Mammalian Paleontology

Background:

• The extinct giant rodent family Dinomyidae is primarily known from incomplete fossil remains, limiting anatomical understanding.
• Fossil discoveries of large extinct mammals are crucial for reconstructing past ecosystems and evolutionary lineages.

Purpose of the Study:

• To describe a new species of giant fossil rodent, Josephoartigasia monesi sp. nov., based on an exceptionally preserved skull.
• To provide new anatomical insights into the extinct Dinomyidae family.
• To reconstruct the paleoenvironment of this newly described species.

Main Methods:

• Fossil excavation and detailed morphological analysis of a well-preserved skull.
• Comparative anatomical study with other known Dinomyidae fossils.
• Paleoenvironmental reconstruction based on geological context and associated flora/fauna.

Main Results:

• Description of Josephoartigasia monesi sp. nov., the largest recorded rodent species with an estimated body mass of approximately 1000kg.
• The skull provides unprecedented detail on Dinomyidae cranial anatomy, previously known mainly from fragmentary evidence.
• The fossil was recovered from the San José Formation in Uruguay, dating to the Pliocene-Pleistocene (4-2 million years ago).

Conclusions:

• Josephoartigasia monesi represents a significant discovery, expanding the known size range and anatomical diversity of extinct rodents.
• This finding enhances our understanding of the evolutionary history and paleoecology of South American Caviomorpha.
• The species inhabited an estuarine or deltaic environment with forest communities during the Pliocene-Pleistocene.