Cetaceans

[Recusant]

. . . That would be the whales and dolphins. A couple of items here. 

The first echoes back to a thread from last year about the sociology of orcas.

"Like humans, beluga whales form social networks beyond family ties" | ScienceDaily

A groundbreaking study using molecular genetic techniques and field studies brings together decades of research into the complex relationships among beluga whales (Delphinapterus leucas) that spans 10 locations across the Arctic from Alaska to Canada and Russia to Norway. The behavior of these highly gregarious whales, which include sophisticated vocal repertoires, suggest that this marine mammal lives in complex societies. Like killer whales (Orcinus orca) and African elephants (Loxodonta Africana), belugas were thought to form social bonds around females that primarily comprise closely related individuals from the same maternal lineage. However, this hypothesis had not been formally tested.

The study, led by Florida Atlantic University's Harbor Branch Oceanographic Institute, is the first to analyze the relationship between group behaviors, group type, group dynamics, and kinship in beluga whales. Findings, just published in Scientific Reports, reveal several unexpected results. Not only do beluga whales regularly interact with close kin, including close maternal kin, they also frequently associate with more distantly related and unrelated individuals.

[. . .]

"Unlike killer and pilot whales, and like some human societies, beluga whales don't solely or even primarily interact and associate with close kin. Across a wide variety of habitats and among both migratory and resident populations, they form communities of individuals of all ages and both sexes that regularly number in the hundreds and possibly the thousands," said [Greg] O'Corry-Crowe [lead author of the paper]. "It may be that their highly developed vocal communication enables them to remain in regular acoustic contact with close relatives even when not associating together."

Beluga whale groupings (beyond mother-calf dyads) were not usually organized around close maternal relatives. The smaller social groups, as well as the larger herds, routinely comprised multiple matrilines. Even where group members shared the same mtDNA lineage, microsatellite analysis often revealed that they were not closely related, and many genealogical links among group members involved paternal rather than maternal relatives. These results differ from earlier predictions that belugas have a matrilineal social system of closely associating female relatives. They also differ from the association behavior of the larger toothed whales that informed those predictions. In 'resident' killer whales, for example, both males and females form groups with close maternal kin where they remain for their entire lives.

"Beluga whales exhibit a wide range of grouping patterns from small groups of two to 10 individuals to large herds of 2,000 or more, from apparently single sex and age-class pods to mixed-age and sex groupings, and from brief associations to multi-year affiliations," said O'Corry-Crowe. "This variation suggests a fission-fusion society where group composition and size are context-specific, but it may also reflect a more rigid multi-level society comprised of stable social units that regularly coalesce and separate. The role kinship plays in these groupings has been largely unknown."

[Continues . . .]

The full paper is open access:

"Group structure and kinship in beluga whale societies" | Scientific Reports

Florida Atlantic University has released a brief video about the study.

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Next, study of an apparent ancestor of the dolphins may revise the understanding of cetacean evolution.

"Massive Predatory Dolphins Once Terrorized Earth's Oceans" | ScienceAlert

Scientists have identified an almost-complete skeleton of a 4.8-metre (15.7-foot) long dolphin ancestor that lived in what is now South Carolina during the Oligocene epoch around 25 million years ago.

This 'dolphin' was the first known echolocating apex predator: as well as its large size, it would've had large, tusk-like teeth, and appears to have been capable of feeding and hunting at high speeds like an orca.

Importantly, the discovery could help us better understand how the two types of modern whales – toothed whales, such as dolphins, and baleen whales, like humpbacks – evolved their unique features, such as flippers and tail propulsion.

The skeleton was found in the 1990s but initially misclassified, and is the first nearly complete Ankylorhiza tiedemani skeleton to be analysed – previously the creature could only be studied from a partial rostrum – or snout – fossil, but now the cetacean can be much more fully understood.

One of the main revelations is that many aspects of the skeleton – the skull and tail shape, the short upper arm bone in the flipper, the shape of the teeth – suggest that the two modern types of whales, toothed and baleen, evolved many of the same features in parallel independently of each other, rather than inheriting them from the same ancestor as previously thought.

[Continues . . .]

The paper appears to be open access--at the link below, click on the DOI link below the title and list of authors to get the PDF.

"Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina" | Current Biology

[xSilverPhinx]

"Massive Predatory Dolphins Once Terrorized Earth's Oceans"

So you mean to tell me was more like ? 



Films are the closest I ever got to cetaceans. Such cool creatures.