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From first tetrapods to live on land up to non-avian dinosaurs wiped out

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375 Million years ago to 65 million years ago

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375 Million years ago to 65 million years ago

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Significant People involved:

Thewissen JGM

Cooper LN

Clementz MT

Bajpai S, Tiwari BN

After dinosaur mass extinction, the earliest cetaceans looked amphibious and eventually evolved to possess mammal features which are far from whales we see today.

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The relationships between cetaceans and their land descendants are depicted in this cladogram. 

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Phylogenetic inference is the study of how organisms are linked to one another, and ideas about phylogeny are represented by a cladogram, a branching diagram that connects more-and-more closely related groups as closer-and-closer branches.

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studied the fossils and identified the origin of the species as well as their natural habitat.

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Significant people involved:
Aslan and Thewissen (1997)

Appearance of first whales (Pakicetus) in the land

It was identified through genetic similarities that Cetaceans have a common ancestor with modern-day artiodactyls such as the cow, pig, camel, giraffe, and hippopotamus

Complex Description for Pakicetus:

Typical land animals

Long skulls and large carnivorous teeth

Ear region resembles those of living whales

1 to 2 meters long

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Water Chevrotain seek refuge in the aquatic habitat; Ambulocetus adapted to life underwater

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Significant People Involved:

Madar SI

Thewissen JGM

Hussain ST

Early ancestors found escape from predators underwater, and also to feed. However, the decision on which role in the food chain they are classified: omnivore or herbivore wasn't clarified.

Complex description for Ambulocetus:

More aquatic lifestyle

Legs are shorter and webbed; hands and feets are enlarged like paddles; longer and more muscular.

Could live in fresh and saltwater alike.

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Ancestor of Modern whales migrated to ultimately reach the ranges of today’s cetaceans 

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Significant People Involved:
A. Ranga Rao

Unclear picture to figure out the migration occurrences of the whales. Bones of Indohyus (closest relative of cetaceans) were found in the Himalaya mountains near the border between Pakistan and India.

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Significant People Involved:
Fordyce E, Muizon Cd (2001)

This is due to rapid ecological changes in the oceans where today’s whales became divided into 2 major groups: odontocetes (toothed whales) and mysticetes (baleen whales)

Introductions to the evolutionary history of odontocetes and mysticetes have been published

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15 milliom years - 4.5 million years ago

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15 milliom years - 4.5 million years ago

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Samples of long sequence 28 circular bones had been examined by the Philadelphia Society.

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Reviewed the fossils donated by Judge H. Bry and Judge John Creagh and noticed similarities to extinct marine reptiles including long-necked plesiosaurs and streamlined ichthyosaurs (Basilosaurus).

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Complex Description for Basilosaurus:

Share traits with marine reptiles

Identified as mammal

Inner ear matched a whale

Carefully scrutinized every bone and studied the teeth sample under the microscope.

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Representation of Basilosaurus Whales as a transitional form

Darwin wrote a small note regarding Basilosaurus while preparing for the 6th edition of his book "Origin of Species

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According to Huxley,  there could be little doubt that Basilosaurus provided clues as to the ancestry of whales

Huxley also thought that Basilosaurus at least represented the type of animal that linked whales to their terrestrial ancestors

Introduction of Squadlon

a fossil dolphin with a wicked smile full of triangular teeth

Huxley said that Squadlon similarly hinted that whales had evolved from meat-eating ancestors.

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He said that cetaceans might have better alternative models for the earliest terrestrial whales, such as semi-aquatic otters & beavers

He also thought that ungulates/hoofed mammals’ skeletal were identical with whales

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Fossils of Basilosaurus were hard to find

E.D. Cope wrote a review regarding whales. According to Cope, "The order Cetacea is one of those of whose origin, we have no definite knowledge.”

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Relationship of Cetaceans & ancient meat-eating mammals were investigated

Van Valen suggested that mesonychids were quite identical with the earliest known whales, because it appears that the teeth of mesonychids were similar with those of the whales' like Protocetus.

Van Valen thought of mesonychids to be marsh dwellers and even suggested that once they had begun swimming for their supper, succeeding generations would become more and more aquatically adapted until something “as monstrous as a whale” evolved

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Discoveries of freshwater sediments with fossils were found in Pakistan. 

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Significant People Involved:
Philip Gingerich
Donald Russel

Philip Gingerich & Donald Russel were able to recover freshwater sediments from approximately 53 million years ago along with fossils from Pakicetus inachus--which were believed to be connected to cetaceans since it exhibited pachyosteosclerosis.

It was also found that the teeth of the Pakicetus from its two jaw fragments were similar to mesonychids--supporting Van Valen's hypothesis of mesonychids being marsh-dwelling animals.

Both paleontologists suggested that Pakicetus were "an amphibious intermediate stage in the transition of whales from land to sea,” though they added the caveat that “Postcranial remains/bones other than the skull will provide the best test of this hypothesis.”

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Pakicetus were presented on televisions & magazines to be a "stumpy-legged, seal-like creature"

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Fossils of Archaeocetes were discovered in Egypt

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Significant person involved:
Dr. B. Holly Smith
Phillip Gingerich

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Artiodactyls were found to be the ancestors of whales rather than mesonychids.

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Significant people involved:
J.G.M. Thewissen & et. al.

Opposed that the fossils of Pakicetus were evidence of an ancient  whale.

suggested that the fossil remains were ong-sought skeleton (as opposed to just the skull) of Pakicetus attocki, depicting it as a wolf-like animal rather than a slick, sea-like animal.

He suggested that the fossils were rather a document regarding the evolutionary radiation of early whales of archaeocetes and not a series of direct ancestors/descendants but fits in the recent discovered genera such as Himalayacetus, Ambulocetus, Remingtonocetus, Kutchicetus, Rodhocetus and Maiacetus.

Suggested that  the earliest form of the famous archaeocetes were the Pakicetus & the slightly older Himalayacetus and were said to be more living in the land thank in the water

Ambulocetus appeared million years later and were described as a whale with a crocodile-like skull and large webbed feet

A long-snouted  long-snouted and otter-like remingtonocetids appeared next, including small forms like the 46-million-year-old Kutchicetus and it appears that these kinds of whale inhabited near-shore environments, encompassing saltwater marshes to shallow sea

At the same time of the existence of remingtonocetids, protocetids also existed, but they are more aquatically adapted. They lived nearly entirely aquatic, and some later protocetids, like Protocetus and Georgiacetus, were almost certainly inhabiting in the sea their entire lives which gave way to fully aquatic whales to expand their ranges to the shores of other continents and diversify, and the sleeker basilosaurids like Dorudon, Basilosaurus and Zygorhiza populated the warm seas of the late Eocene

However, these creatures deceased, yet gave rise to early representatives of two groups of whales existing currently, the toothed whale & baleen whale

The astragalus (an ankle bone) from artiodactyls were described as having a "double pully" shape, were not present in mesonychids. However, archaeocetes which have this kind of bones were described, which confirms that cetaceans evolved from artiodactyls. It was found that Mesochynids were not the ancestors of whales & hippos.

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Introduction of Indohyus as a relative to whales.

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Significant person involved:
J.G.M. Thewissen

A student from Thewissen's lab found that the inner ear of the Indohyus where similar to the bones in whale ears, moreover, the skeleton also contains bones marked by an identical type of thickening, which is an adaptation shared by mammals that spent a lot of time in the water, therefore, regarding Indohyus (a deer-like mammal) belongs to raoellids (group of extinct artiodactyls), which was, apparently, the closest relative to whales.

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A new whale family was discovered.
Jonathan Geisler & Jennifer Theodor
Combined genetic data with fossils data discovering a new family tree & whales were finally firmly rooted in the mammal evolutionary tree

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Four-legged Whale fossils found in Peru .

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An international team of palaeontologists from Peru, France, Italy, the Netherlands, and Belgium

the discovered fossils were said to be four meter long (13 ft) and was adapted to swim & walk on land.

It was discovered in marine sediments inland from Peru's pacific coast, at Playa Media Luna, and is said to be "the most complete specimen ever found for a four-legged whale outside of India & Pakistan" by Dr. Oliver Lambert.

It was named Peregocetus Pacificus which means "the travelling whale that reached the Pacific".

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The world’s rarest whale species, spade-toothed whale, was confirmed in New Zealand.

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Thompson et al. (2012) conducted DNA analysis which revealed the identity of the world’s rarest whale, the spade-toothed beaked whale (Mesoplodon traversii).

Thompson et al. (2012) yielded the first morphological description and photos of the mysterious species.

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Shipping noise in the North Atlantic impact on whale population levels

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Blaire et al. (2016) gathered evidence that suggests exposure to low-frequency ship noise may be linked to chronic stress in whales, which has consequences for all baleen whales in high-traffic locations as well as the recovery of the endangered right whale population.

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A new species of beaked whale of the genus Berardius, Berardius minimus,  was found in the North Pacific Ocean.

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Yamada et al. (2019) provided morphological evidence which recognized a new species of the genus Berardius (giant beaked whale) and named them Berardius minimus. Yamada et al. (2019) described the new species as whales with a unique appearance - having a significantly smaller body size than physically mature adults, a proportionately shorter beak, a darker body color, and visible cookie-cutter shark bites.

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Recovery of humpback whales after commercial whaling. 

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Dr. Kirsten Thompson

study from Zerbini & et. al., suggests that from the coast of Brazil and Antarctic waters, it was found that during summer, the whales can now be found in sort of numbers.

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A new species of whale, Rice’s whale has been identified in the Gulf of Mexico.

Rice’s whale is a member of the Balaenopteridae family of baleen whales (Southeast Regional Office, 2021).

They are one of the world's most endangered whales, with potentially fewer than 100 individuals left (Southeast Regional Office, 2021).

Rice’s whale is named after Dale Rice, a marine mammal scientist who discovered the species in the Gulf of Mexico (Southeast Regional Office, 2021).

Dr. Patricia Rosel

Dr. Rosel examined the first genetic data gathered from NOAA Fisheries vessel surveys in the Gulf of Mexico (Fisheries, 2021).

She discovered a collection of bones near the top of the skull that separates Rice's whales from other species (Cowan, 2021).

Dr. Rosel published findings in Marine Mammal Science in 2021 that confirmed that Rice’s whales in the Gulf of Mexico are not Bryde’s whales (Cowan, 2021).

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BBC News. (2019, April 05). Fossil of ancient four-legged whale found in Peru. Retrieved September 19, 2021, from https://www.bbc.com/news/science-environment-47822228

Black, Riley. (2010, December 01). How Did Whales Evolve? Smithsonian Magazine. Retrieved September 19, 2021, from https://www.smithsonianmag.com/science-nature/how-did-whales-evolve-73276956/

Berkeley. (n.d.). Evolution of Whales. Retrieved September 19, 2021, from https://evolution.berkeley.edu/evolibrary/article/evograms_03

Blair, H. B., Merchant, N. D., Friedlaender, A. S., Wiley, D. N., & Parks, S. E. (2016). Evidence for ship noise impacts on humpback whale foraging behaviour. Biology Letters, 12(8). https://doi.org/10.1098/rsbl.2016.0005

Fisheries, N. (2021, February 3). New Species of Baleen Whale in the Gulf of Mexico. Environmental News Network. https://www.enn.com/articles/66966-new-species-of-baleen-whale-in-the-gulf-of-mexico

How the Rice’s Whale Became a New Species. (2021, February 18). Smithsonian Magazine. https://www.smithsonianmag.com/science-nature/how-rices-whale-became-new-species-180977009/

Southeast Regional Office. (2021, January 22). New Species of Baleen Whale in the Gulf of Mexico. National Oceanic and Atmospheric Administration. https://www.fisheries.noaa.gov/feature-story/new-species-baleen-whale-gulf-mexico

Thompson, Kirsten. (2020, May 16). Humpback Whales Have Made a Remarkable Recovery, Giving Us Hope for the Planet. TIME. Retrieved September 19, 2021, from https://time.com/5837350/humpback-whales-recovery-hope-planet/

Thompson, K., Baker, C. S., van Helden, A., Patel, S., Millar, C., & Constantine, R. (2012). The world’s rarest whale. Current Biology, 22(21), R905–R906. https://doi.org/10.1016/j.cub.2012.08.055

Yamada, T. K., Kitamura, S., Abe, S., Tajima, Y., Matsuda, A., Mead, J. G., & Matsuishi, T. F. (2019). Description of a new species of beaked whale (Berardius) found in the North Pacific. Scientific Reports, 9(1). https://doi.org/10.1038/s41598-019-46703-w

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Leaders:
Macarubbo, Eyer Toofiel A.
Mendoza, Aubrey Anne Dominique
Members
Alagos, Sheena Mae
Lagaya, Raine
Moril, Phoemela Nicole
Obispo, Mikhaella