Paleontologists in Peru have unearthed a nearly complete skeleton of a 12-million-year-old marine dolphin in the Ocucaje Desert. The specimen, identified as Lomacetus, measures approximately 3.5 meters and is in exceptional condition, offering a rare window into a bygone era. This remarkable find is particularly noteworthy as Lomacetus exhibits characteristics similar to modern porpoises found along the Peruvian coast, suggesting a shared evolutionary path. Researchers anticipate that this fossil will yield invaluable insights into the locomotion, diet, and lifespan of this ancient species.
The Ocucaje Desert, situated south of Lima, is globally recognized as a premier paleontological site. This region was once a thriving sea, attracting a diverse array of species for reproduction for over 45 million years. The unique geological conditions of the area have preserved a rich tapestry of marine life, with previous expeditions uncovering fossils of four-legged whales, prehistoric sharks, and giant turtles. Notably, a 16-million-year-old Amazonian river dolphin skull was discovered here in 2024, further cementing the desert's importance in understanding marine biodiversity.
The Lomacetus fossil adds to this legacy, contributing to the limited knowledge of its genus, which belongs to the Kentriodontidae family—an intermediate group in the evolution of modern toothed whales. Its presence in the South Pacific raises questions about ancient migratory routes during the Miocene epoch. Mario Urbina, one of the lead researchers, emphasized Ocucaje's status as a rich fossil repository. The transformation of this ancient seabed into the desert landscape is attributed to tectonic movements and climate change over millions of years.
These geological shifts have preserved the remains of marine life, offering crucial data for understanding the evolution of Peru's coastal geography and the significant shifts in its past coastlines, climates, and landscapes. The Middle Miocene, spanning from 15 to 11 million years ago, experienced a global warming event known as the Mid-Miocene Climatic Optimum. This period likely fostered warmer, more stable conditions for marine life in regions like Peru, supporting a rich diversity of marine mammals.
The Lomacetus fossil is poised to open new avenues for research across paleontology, geology, and evolutionary biology, reinforcing Peru's pivotal role in the study of fossil marine species and their adaptation to environmental changes. Following extensive analysis, the fossil is expected to be housed in national museums, serving as a vital educational resource about Peru's natural heritage. The Ocucaje Desert faces conservation challenges such as fossil poaching and urban expansion, underscoring the need for legal protection to safeguard this invaluable scientific and historical legacy.
The region, primarily within the Pisco Formation, is known for its Miocene and Pliocene marine sediments, with over 60% of marine fossils found in Peru in the last two decades originating from this area, according to Ingemmet.