26 Small origins for baleen whales, the largest animals to ever live
Cetacea, Mysticeti: Toipahautea waitaki
The largest animal to have ever lived (that we know about) is the blue whale Balaenoptera musculus, which reaches almost 30 metres in length and has a global distribution. The blue whale feeds almost exclusively on krill, which are a collection of jointed-limb animals with external skeletons (species within Arthropoda) that look similar to shrimp. As with all living mysticetes, blue whales capture their food by squeezing a mouthful of water out past plates of keratin that hang from their jaws in the place of teeth. Krill become trapped on the inside of these keratin or baleen plates and the whale uses its tongue to hoover up the food. Baleen plates are clearly important for the success of mysticetes, and so the evolutionary origins of baleen has been an important question in paleontological research. Understanding the early origins of baleen whales has been a major research theme for the Department of Geology at the University of Otago.
The top image shows the incomplete skull of the fossil whale Toipahautea waitaki (specimen OU 21981). In this view the snout of the whale is pointing towards the right and we are looking at the top of the head (dorsal surface). The lower left image shows other assorted bones from the fossil and the lower right image shows Cheng-Hsiu Tsai studying the fossil for his doctoral thesis research. Image credit: RE Fordyce. |
In 2018 Cheng-Hsiu Tsai and Ewan Fordyce described Toipahautea waitaki, the oldest fossil whale ever discovered that did not have teeth. Like all mammals, including their close dolphin relatives, the ancestors of baleen whales had teeth. Baleen would come to replace teeth during the evolutionary history of mysticetes, and so for a time there were ancient whales that had both baleen and teeth (e.g. Aetiocetus cotylalveus). This was a transitional time in whale evolutionary history when baleen was becoming more important for collecting food, beginning when the earliest forms of baleen evolved, and ending when baleen whales no longer had teeth erupting from their jaws. Toipahautea waitaki is the fossil whale that currently represents the end of that transitional period.
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Did you know there is a 3D printable model of this fossil for you to view online and download? Follow this link to learn more: 3D model—Small origins for baleen whales, the largest animals to ever live. |
Toipahautea waitaki is important for helping researchers understand how long the transition from teeth to baleen took and how big ancient whales were when they began to rely only on baleen for food collecting. Toipahautea waitaki was discovered in the 1980s in a limestone quarry in the Hakataramea Valley in South Canterbury and was recovered in 1988 by Ewan Fordyce, Andrew Grebneff and Craig Jones. Upon preparation at the Department of Geology the fossil was revealed to be a partial skeleton with bones from the upper skull, lower jaws, vertebrae, scapulae, parts of the flippers, and some ribs. Keratin tends to decompose and not preserve in the fossil record, so no baleen was recovered. Instead, the upper skull preserves grooves that would have housed the blood vessels that supplied the baleen when the animal was living, as in baleen whales today. From these blood vessel grooves and several other features Tsai and Ewan were able to conclude that Toipahautea waitaki would have originally used baleen to help with feeding. No teeth were found with the whale and the jaws did not have sockets for teeth.
Toipahautea waitaki lived around 27.5 million years ago and is estimated to have been around five metres long. This is smaller than the adult size of the pygmy right whale Caperea marginata which is the smallest baleen whale living today. Toipahautea waitaki shows that baleen whales had relatively humble beginnings and that that it would be many millions of years before they approached the size of today’s ocean giants.
—Written by Daniel B Thomas
| Specimen number: OU 21981 | Age: Approximately 27.5 million years ago (late Oligocene, upper Whaingaroan stage) |
| Locality: Hakataramea Valley, South Canterbury | Rock Formation: Kokoamu Greensand |
| Collected by: RE Fordyce, A Grebneff, CM Jones | |
| Citation: Tsai CH, Fordyce RE. 2018. A new archaic baleen whale Toipahautea waitaki (early Late Oligocene, New Zealand) and the origins of crown Mysticeti. Royal Society Open Science 5:172453. doi:10.1098/rsos.172453 | |
Marine mammals within Cetacea that have large keratin plates (baleen) for filtering food from water. One of two major clades within Neoceti, with the other being Odontoceti. Living examples include blue whale (Balaenoptera musculus) and southern right whale (Eubalaena australis).
A protein that provides structural support to many epidermal tissues including hair and nails of mammals, feathers of birds, scales of reptiles.
Cartilage plates suspended from the upper jaw in the mouth of mysticete whales. Used to strain prey from sea water.
Evidence of life from a past geological age. Remains like bones, shells or wood, or an impression like a footprint, or some other evidence of life, from something that was alive more than 11,700 years ago.
A smaller species within Cetacea, and one that has teeth. The precise taxonomic definition for dolphin is any species within Delphinidae, Platanistidae, Iniidae, Pontoporiidae and Lipotidae. However, dolphin is also used for close extinct relatives of living dolphins that are not included in these families.
A sedimentary rock composed mainly of calcium carbonate. Can be formed from the skeletal fragments of marine organisms.
An inland location within southernmost Canterbury, New Zealand, where significant fossil discoveries have been made.
The series of bones forming the flexible 'backbone' structure of the animals named for possessing these bones, the vertebrates.
Bones in the shoulders where muscles from the forelimb are attached. More commonly known as shoulder blade.
The process by which organic structures like animal bodies or tree trunks are broken down into simpler organic matter.
A collection of fossils that document the history of life. Reference might be made to the history of life in a particular place ('the fossil record of New Zealand'), or the history of a particular group of organisms ('the fossil record of penguins'), or simply the global history of all life ('the fossil record').
