Desmostylians Vacuumed up Their Aquatic Plants Diet, Didn't Chew

The identification of a new species belonging to the marine mammal group Desmostylia has intensified the rare animal's brief mysterious journey through prehistoric time, finds a new study.

A big, hippo-sized animal with a long snout and tusks -- the new species, 23 million years old, has a unique tooth and jaw structure that indicates it was not only a vegetarian, but literally sucked vegetation from shorelines like a vacuum cleaner, said vertebrate paleontologist and study co-author Louis L. Jacobs, Southern Methodist University, Dallas.

But unlike other marine mammals alive today -- such as whales, seals and sea cows -- desmostylians went totally extinct. Desmostylians, every single species combined, lived in an interval between 33 million and 10 million years ago.

Their strange columnar teeth and odd style of eating don't occur in any other mammal, The new specimens -- from at least four individuals -- were recovered from Unalaska, an Aleutian island in the North Pacific.

While alive, the creatures lived in what is now Unalaska's Dutch Harbor, where fishing boats depart on Discovery channel's "Deadliest Catch" reality TV show.

"The new animal -- when compared to one of a different species from Japan -- made us realize that desmos do not chew like any other animal," said Jacobs, a professor of earth sciences. "They clench their teeth, root up plants and suck them in."

To eat, the animals buttressed their lower jaw with their teeth against the upper jaw, and used the powerful muscles that attached there, along with the shape of the roof of their mouth, to suction-feed vegetation from coastal bottoms. Big muscles in the neck would help to power their tusks, and big muscles in the throat would help with suction.

"No other mammal eats like that," Jacobs said. "The enamel rings on the teeth show wear and polish, but they don't reveal consistent patterns related to habitual chewing motions."

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California Blue Whales Have Recovered to Near Historical Levels

The number of California blue whales has rebounded to near historical levels, according to new research by the University of Washington, and while the number of blue whales struck by ships is likely above allowable U.S. limits, such strikes do not immediately threaten that recovery.

This is the only population of blue whales known to have recovered from whaling – blue whales as a species having been hunted nearly to extinction.

Blue whales – nearly 100 feet in length and weighing 190 tons as adults – are the largest animals on earth. And they are the heaviest ever, weighing more than twice as much as the largest known dinosaur, the Argentinosaurus. They are an icon of the conservation movement and many people want to minimize harm to them, according to Trevor Branch, UW assistant professor of aquatic and fishery sciences.

"The recovery of California blue whales from whaling demonstrates the ability of blue whale populations to rebuild under careful management and conservation measures," said Cole Monnahan, a UW doctoral student in quantitative ecology and resource management and lead author of a paper on the subject posted online Sept. 5 by the journal Marine Mammal Science. Branch and André Punt, a UW professor of aquatic and fisheries sciences, are co-authors.

California blue whales ¬ are at their most visible while at feeding grounds 20 to 30 miles off the California coast, but are actually found along the eastern side of the Pacific Ocean from the equator up into the Gulf of Alaska.

Today they number about 2,200, according to monitoring by other research groups. That's likely 97 percent of the historical level according to the model the co-authors used. That may seem to some a surprisingly low number of whales, Monnahan said, but not when considering how many California blue whales were caught. According to new data Monnahan, Branch and another set of co-authors published earlier this summer in PLOS ONE, approximately 3,400 California blue whales were caught between 1905 and 1971.

"Considering the 3,400 caught in comparison to the 346,000 caught near Antarctica gives an idea how much smaller the population of California blue whales was likely to have been," Branch said.

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The Impact of Climate Change on Antarctic fur Seals

Genetic analysis of Antarctic fur seals, alongside decades of in-depth monitoring, has provided unique insights into the effect of climate change on a population of top-predators. Published in Nature this week, the findings show that the seals have significantly altered in accordance with changes in food availability that are associated with climate conditions. Despite a shift in the population towards 'fitter' individuals, this fitness is not passing down through generations, leaving the population in decline.

Environmental change is expected to affect many species and biological systems throughout the world. To understand these changes long-term monitoring is required. The British Antarctic Survey's unique Long Term Monitoring and Survey programme has given researchers a rare opportunity to explore how fur seal life histories have changed over time in relation to the climate and food availability.

Researchers from the British Antarctic Survey and Bielefeld University in Germany analysed data gathered from as far back as 1981 to assess changes over generations of female fur seals on South Georgia, in the South Atlantic Ocean.

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Sirenians Evolved in Parallel to Climate Change in Paleogene to Neogene Europe and North Africa

Euro-North African Sirenia biodiversity as a response to climate variations

Authors:

Prista et al

Abstract:

Earth has a latitudinal biodiversity gradient in which more species inhabit tropical than polar regions. Frequently attributed to seasonality, this ecological pattern is applied to the evolution of the Euro-North African sirenians and its relation to Cenozoic climate change. Climate disruption, changes in seasonality, and geological processes such as sea level variations are statistically tested as primary drivers to explain sirenian evolution and regional (amphi-Mediterranean) sirenian speciation and biodiversity.

Drivers of Marine Tetrapod Evolution From the Triassic Mesozoic to the Quaternary Cenozoic

Marine tetrapod macroevolution: Physical and biological drivers on 250 million years of invasions and evolution in ocean ecosystems

Authors:

Pyenson et al

Abstract:

The dominant consumers in today’s ocean ecosystems are marine mammals, including cetaceans, sirenians, and pinnipeds, and other marine carnivorans. The ecological dominance of marine mammals can be traced back to at least seven independent transitions during the Cenozoic, when different lineages of terrestrial mammals underwent land to sea evolutionary transformations. However, the evolution of marine mammals represents only the most recent set of marine invasions by tetrapods over the past 250 million years. During the Mesozoic, over a dozen different reptile lineages (e.g., mosasaurs, ichthyosaurs, turtles, snakes) evolved obligate marine lineages, including a few lineages that persist to today, such as sea turtles. Birds, which are phylogenetically nested among diapsid reptiles, have also repeatedly adapted to marine life since the Cretaceous. Attempts to understand the common patterns of marine tetrapod evolution, and the processes that have shaped them, have largely been limited to individual groups. Placed in a broad comparative view from the Mesozoic to the Cenozoic eras, the macroevolution of marine tetrapods reveals evolutionary drivers at different scales, along with morphological parallels, unique evolutionary innovations, and the strong influence of historical constraints. Major physical, environmental drivers appear to be responsible for some patterns in marine tetrapod evolution at some temporal and geographic scales, but these drivers are not unique causes, as biological drivers (e.g., escalation) likely also play a role. The culmination of this trophic ascendancy has been dramatically altered by human hunting (especially of marine mammals), underscoring the need for historical datasets that extend into deep time to understand the ecological history of marine tetrapods.

Fossil Ambergris Found

Clumps of squid beaks sticking out of clay in Italy's Umbrian badlands may be the first fossilized ambergris, or whale poo, ever found.

Ambergris is a fatty, waxy-looking substance. Scientists believe sperm whales — the largest toothed predator on Earth — secrete ambergris inside their digestive tracts to protect themselves from sharp objects, like giant squid beaks and fish bones and teeth. And contrary to urban legend, ambergris is actually whale poo, not vomit. Sought after by perfume makers, aged ambergris is like umami for the nose, adding musky depth to scents.

Even though scientists have discovered fossilized feces, called coprolites, from dinosaurs, ichthyosaurs, mammoths and sharks, no one has reported finding ancient ambergris.

Good thing King Charles II isnt alive: might crack his teeth.  He'd have to use fossilized eggs to go with though.

Extinction of Sirenia of Europe and North Africa

The disappearance of the European/North African Sirenia (Mammalia)

Authors:

1. Gonçalo Prista (a)
2. Mário Estevens (c)
3. Rui Agostinho (d)
4. Mário Cachão (a, b)

Affiliations:

a. Centre of Geology of the University of Lisbon, Campo Grande, 1749-016 Lisbon, Portugal

b. Faculty of Sciences of the University of Lisbon, Geology Department, Campo Grande, 1749-016 Lisbon, Portugal

c. Almada City Council, Departamento de Estratégia e Gestão Ambiental Sustentável Ecoteca de Almada - Casa Municipal do Ambiente R. Bernardo Francisco da Costa, nº 40 e nº 42 2800-029 Almada, Portugal

d. Faculty of Sciences of the University of Lisbon, Physics Department, Campo Grande, 1749-016 Lisbon, Portugal

Abstract:

Sirenia inhabited the coastal waters of Europe and North Africa from the Eocene until the end of the Pliocene. They are the only herbivorous marine mammals, and their presence in the European/North African realm is supported by almost 400 fossil records. Their dependence on seagrass, as well as their ecological needs, limited their capability to adapt to the climate changes that occurred during the Cenozoic. Their disappearance from European and Mediterranean shores occurred in two different steps: 1) the European Atlantic extinction, related to global cooling and fragmentation of the seagrass meadows, which greatly reduced sirenia habitats and resources; 2) their disappearance from the Mediterranean, linked not to declining resources but to the onset of continental glaciations in the northern hemisphere.

A Pleistocene Cetothere Fossil From Northern California

Research from New Zealand's University of Otago detailing the fossil of a dwarf baleen whale from Northern California reveals that it avoided extinction far longer than previously thought.

Otago Department of Geology PhD student Robert Boessenecker has found that the fossil of the 4-5 meter long Herpetocetus, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old.

Mr Boessenecker says the previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago.

"That this whale survived the great climatic and ecological upheavals of the Ice Age and almost into the modern era is very surprising as nearly all fossil marine mammals found after the end of the Pliocene appear identical to modern species.

"Other baleen whales underwent extreme body size increases in response to the new environment, but this dwarf whale must have still had a niche to inhabit which has only recently disappeared," he says.

The find indicates that the emergence of the modern marine mammals during the Ice Age may have happened more gradually than currently thought, he says.

The discovery also lends indirect support to a hypothesis about the modern pygmy right whale (Caperea marginata) recently published by Mr Boessenecker's colleagues Professor Ewan Fordyce and Dr Felix Marx. The pair posited that this enigmatic Southern Ocean whale is not a true right whale but actually a member of the cetothere family and one of the closest relatives of Herpetocetus.

"If their hypothesis is correct, this latest discovery indicates that other close relatives of the pygmy right whale nearly survived to modern times within the Northern Hemisphere.

"In this light, Herpetocetus can be viewed as a Northern Hemisphere equivalent of the pygmy right whale: both are small-bodied with peculiar anatomy, possibly closely related, with feeding habits that are seemingly divergent from other baleen whales."