Type specimen (holotype) of Pebanista yacuruna, including a photo of the specimen and a surface 3D model in dorsal view.
Image: Aldo Benites-Palomino.
The third in a clutch of very recent papers casually refuting the childish beliefs of the creation cult.
This one concerns a giant freshwater dolphin that inhabited the Amazon 16 million years before creationists think there was a Universe, let alone an Earth with life on it.
Tell me about the Peruvian Amazon 16 million years ago. Around 16 million years ago, during the Middle Miocene epoch, the Peruvian Amazon region would have been significantly different from its present-day appearance. This period falls within the broader geological timeframe known as the Neogene Period, characterized by significant changes in climate and biodiversity.The news comes from a team of paleontologists led by Aldo Benites-Palomino from the Department of Paleontology in the University of Zürich, Switzerland.
During this time, the Amazon basin was undergoing a transformation from a relatively dry environment to a more humid and tropical one. The climate was warmer and wetter compared to today, with vast stretches of lush tropical rainforest covering much of the region.
The landscape would have been dominated by dense forests, rich in diverse flora and fauna. Ancient ancestors of many of today's Amazonian species would have been present, including various types of plants, mammals, birds, reptiles, and insects. Megafauna such as giant ground sloths, glyptodonts, and various types of large herbivores and predators may have roamed the area.
The river systems of the Amazon basin would have been different as well, as the Andes Mountains continued to uplift and shape the landscape. However, the basic hydrological structure of the Amazon River and its tributaries would have already been established, providing the necessary water sources for the flourishing ecosystems.
Overall, the Peruvian Amazon 16 million years ago would have been a vibrant and biodiverse ecosystem, albeit with species compositions and environmental conditions differing from those of today due to ongoing geological and climatic changes over millions of years.
The team have just published their findings open access in the journal Science Advances together with a news release from the University of Zürich:
Measuring between 3 to 3.5 meters, 16 million years old: Paleontologists from the University of Zürich have announced the discovery of a new species of freshwater dolphin in the Peruvian Amazon region. Surprisingly, its closest living relatives can be found in the river dolphins of South Asia.
River dolphins are among the rarest modern cetaceans, with most extant species critically endangered. Despite their similar appearance, however, these animals are not directly related, but represent the late survivors of different cetacean groups that once inhabited our planet.
An international research team led by the University of Zürich (UZH) has now revealed the largest river dolphin ever found, measuring between 3 and 3.5 meters. The new species, named Pebanista yacuruna after a mythical aquatic people believed to inhabit the Amazon basin, was found in Peruvian Amazonia and is dated to be 16 million years old.
Changing landscape drove giant dolphin to extinction
The new dolphin species belongs to the Platanistoidea, a group of dolphins that were common in the world’s oceans between 24 and 16 million years ago. The researchers believe that their originally marine ancestors invaded the prey-rich freshwater ecosystems of proto-Amazonia and adapted to this new environment.
This landscape included aquatic, semi-aquatic and terrestrial ecosystems (swamps, floodplains, etc.) and stretched across what is today Colombia, Ecuador, Bolivia, Peru and Brazil. When the Pebas system began to give way to modern Amazonia about 10 million years ago, new habitats caused Pebanista's prey to disappear, driving the giant dolphin to extinction. This opened an ecological niche that was exploited by relatives of today’s Amazon river dolphins (Inia), which were also facing extinction in the oceans due to the rise of new cetaceans, such as modern oceanic dolphins.Sixteen million years ago, the Peruvian Amazonia looked very different from what it is today. Much of the Amazonian plain was covered by a large system of lakes and swamps called Pebas.
Aldo Benites-Palomino, lead author
Department of Paleontology
University of Zürich, Zürich, Switzerland.
Findings shed light on the evolutionary history of freshwater dolphinsPebanista and Platanista both share highly developed facial crests, which are specialized bony structures associated with echolocation – the ability to “see” by emitting high-frequency sounds and listening or their echoes, which they rely on heavily for hunting.We discovered that its size is not the only remarkable aspect. With this fossil record unearthed in the Amazon, we expected to find close relatives of the living Amazon river dolphin – but instead the closest cousins of Pebanista are the South Asian river dolphins (genus Platanista).
Aldo Benites-Palomino
The elongated snout with many teeth suggests that Pebanista fed on fish, as other species of river dolphins do today.For river dolphins, echolocation, or biosonar, is even more critical as the waters they inhabit are extremely muddy, which impedes their vision.
Gabriel Aguirre-Fernández, co-corresponding author
Department of Paleontology
University of Zürich, Zürich, Switzerland.Finding Fossils in the AmazonAfter two decades of work in South America we had found several giant forms from the region, but this is the first dolphin of its kind. We were especially intrigued by its peculiar biogeographical deep-time history.
Marcelo R. Sánchez-Villagra, co-author
Department of Paleontology
University of Zurich, Zürich, Switzerland.
. The Amazon rainforest is one of the harshest regions for paleontological fieldwork. Fossils are only accessible during the dry season, when river levels are low enough to expose the ancient fossil-bearing rocks. If these fossils are not collected in time, the rising water levels during the rainy season will sweep them away and they will be lost forever.International team of palaeontologists during the 2018 expedition to the Napo.Image: Aldo Benites-Palomino
The holotype – a single physical specimen on which the description and name of a new species is based – of Pebanista was found in 2018, when the lead author of the study was still an undergraduate student. The expedition, led by Peruvian paleontologist Rodolfo Salas-Gismondi, former postdoctoral fellow at the Department of Paleontology at UZH, traversed more than 300 kilometers of the Napo River.
Dozens of fossils were discovered and collected, but the biggest surprise waited at the end of the expedition, after almost three weeks of exploration: the discovery of the large dolphin skull, catalogued as MUSM 4017, which has been permanently deposited in the Museo de Historia Natural in Lima.
AbstractThe traditional way creationists cope with this sort of news is to either lie about the science and scientists or pretend they know what dating methods were used and why they were either flawed or falsified to make 10,000 years or less look like 16 million years, but they never say how they know or what the flaw is. Like most other ways they've been conditioned to cope with evidence that refutes their core superstitions, creationist objections never amount to more than reflexively parroting traditional mindless squawks.
Several dolphin lineages have independently invaded freshwater systems. Among these, the evolution of the South Asian river dolphin Platanista and its relatives (Platanistidae) remains virtually unknown as fossils are scarce. Here, we describe Pebanista yacuruna gen. et sp. nov., a dolphin from the Miocene proto-Amazonia of Peru, recovered in phylogenies as the closest relative of Platanista. Morphological characters such as an elongated rostrum and large supraorbital crests, along with ecological interpretations, indicate that this odontocete was fully adapted to fresh waters. Pebanista constitutes the largest freshwater odontocete known, with an estimated body length of 3 meters, highlighting the ample resource availability and biotic diversity in the region, during the Early to Middle Miocene. The finding of Pebanista in proto-Amazonian layers attests that platanistids ventured into freshwater ecosystems not only in South Asia but also in South America, before the modern Amazon River dolphin, during a crucial moment for the Amazonian evolution.
INTRODUCTION
Cetacean freshwater transitions occurred in several areas asynchronously during the Neogene. Modern “river dolphins” arose from such events, as the similar morphology of these only distantly related taxa is the result of a clear convergent evolution (1, 2). Among odontocetes (toothed cetaceans), four clades of river dolphins are recognized (Fig. 1A): Iniidae, Lipotidae, Platanistidae, and Pontoporiidae (2, 3). The Yangtze river dolphin Lipotes vexillifer (Lipotidae) had fully riverine habits but was declared extinct a couple decades ago (4, 5). Among the extant taxa, only Platanista (Platanistidae) and Inia (Iniidae) are strictly freshwater inhabitants (6), as the La Plata dolphin Pontoporia blainvillei (Pontoporiidae) roams shallow coastal waters.
Platanista from the South Asian river systems (Fig. 1) is one of the most enigmatic toothed cetaceans and unique by bearing enlarged, thin and pneumatic supraorbital crests that enclose the melon, a fatty structure integral to the echolocation system, which the animal uses to locate and capture prey in muddy waters. Echolocation in Platanista is so dominant that the animal is almost blind (7). The evolutionary history of Platanista (8) and kin remains elusive because fossil data of close relatives are restricted to marine forms such as Araeodelphis, Pomatodelphis, Prepomatodelphis, and Zarhachis (2, 3). Contrarily, distant Platanistoidea relatives are one of the most diverse and frequently fossilized cetaceans, with records ranging from the Late Oligocene until the Middle Miocene. A similar situation pertains to the South American river dolphin Inia (Iniidae), whose fossil relatives have mostly been found in marine environments (9–11), with the exception of Ischyrorhynchus from the Late Miocene of Argentina (12). The overall fossil record of river dolphins is of limited value because the factors that led to repeated freshwater lifestyles from marine ancestors in Cetacea would preferably require fossils of freshwater forms (13, 14).Fig. 1. Biogeographical and paleobiogeographic distribution of Iniidae and Platanistidae through the Neogene.
Schematic representation of the region highlighting the presence of epicontinental waters in South America (pale blue). Extant geographical ranges of the Amazon river dolphin Inia and the South Asian river dolphins Platanista (A). Distribution of fossil Iniidae/Platanistidae records in the Early to Middle Miocene Pebas System (B) and Late Miocene Acre System (C). Modified from Benites-Palomino et al. (14).
Here, we describe a previously unknown platanistid dolphin found in Early to Middle Miocene layers of Peruvian Amazonia. Its holotype skull is characterized by a robust and long rostrum with enlarged teeth, well-developed supraorbital crests, a large temporal fossa, and a deep circumnarial basin. A series of phylogenetic analyses place the new taxon as a sister group to extant Platanista, thus demonstrating that at least two clades of odontocetes (Platanistidae and Iniidae) transitioned into freshwater environments in South America. Size estimations based on cranial measurements of the holotype of the new species and specimens referred to the same genus indicate that the new dolphin likely is the largest known freshwater odontocete, at 2.8 to 3.5 m at a minimum, surpassing the 2.5-m maximum size of modern “river” dolphins. Such a large body size, also recorded in other proto-Amazonia inhabitants (i.e. fishes and crocodilians), might be attributed to the large resource availability in proto-Amazonian ecosystems (15–18). Additional factors that may have contributed to the great body size of this new taxon include the lack of direct predators and competitors in the Pebas mega-wetland system. This finding confirms not only an independent marine-freshwater transition of cetaceans in South America but also that this diversity in the vast Pebas mega-wetland system might have greatly benefited from the warmer Middle Miocene climatic conditions in the area.
Etymology
The generic name Pebanista stresses the relationship between this taxon from the Pebas Fm. (section S1) and the extant Ganges and Indus river dolphins Platanista (Platanista gangetica and Platanista minor). The specific Kichua (northern Quechua) name honors the “yacuruna,” a mythical water creature in the Peruvian Amazonia.
Fig. 2. Pebanista yacuruna gen. et sp. nov., MUSM 4017.
Holotype skull in dorsal (A and B), ventral (C and D), left lateral (E and F), and anterodorsal views (F and G).
Fig. 3. Phylogenetic relationships of Pebanista yacuruna gen. et sp. nov. and the evolutionary context of Platanistoidea within proto-Amazonia.
Adams consensus from three most parsimonious trees (A); eustatic sea level evolution (63) across the mid-Late Neogene (B); diversity of Platanistoidea (28) versus other Odontoceti clades (C); geographical evolution (49, 50) of the Neotropical region (D).
Fig. 4. Size comparison between “river dolphins” and marine platanistoids and river dolphins.
White silhouettes indicate the minimum body length calculated or recorded; gray body outlines indicate the largest size recorded or estimated in: Macrosqualodephis ukupachai† (A), Zarhachis flagellator† (B), P. blainvillei (C), Pebanista yacuruna† gen. et sp. nov. (D), Inia geoffrensis (E), Platanista gangetica (F), and Lipotex vexillifer (G). Artistic reconstruction of Pebanista yacuruna gen. et sp. nov. by Jaime Bran (H).
Aldo Benites-Palomino et al.
The largest freshwater odontocete: A South Asian river dolphin relative from the proto-Amazonia.
Sci. Adv. 10, eadk6320 (2024). DOI:10.1126/sciadv.adk6320
Copyright: © 2024 The authors.
Published by American Association for the Advancement of Science. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
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