March of the Fossil Penguins

Fossil penguin discoveries and research

Kairuku’s world

with 8 comments

What was the world like when Kairuku penguins lived?  It was quite different from today.  Zealandia – a formal name for proto-New Zealand bore little resemblance to its modern day configuration.  Sea level in the region was relatively higher, both because the main islands of  Zealandia were not as uplifted as they are today and because there were no permanent polar ice sheets, leaving more water in the oceans instead of locked away as ice.  Thus, shallow seas submerged large swathes of the South Island,where Kairuku fossils have been recovered.  It was a great place to be a penguin.  The small emergent parts of the South Island would have been safe breeding grounds, given the remoteness from other land masses and lack of terrestrial predators to disturb nests.

Fossil bones of Kairuku penguins are found in a rock formation called the Kokoamu Greensand.  As the name implies, this formation is primarily composed of greenish sedimentary rock formed when seafloor sediments were compressed and became lithified. Several types of sediments are mixed in different layers, including fine quartz sand, calcareous sands, and clays.  The sandstones are heavily bioturbated – that is, mixed up by the borrowings of animals. The seafloor was teaming with life, both on the surface and beneath. Some of the most common invertebrate fossils in the Kokoamu Greensand are shells of the brachiopod WaipariaBrachiopods are shellfish that belong to a whole different class than the bivalve mollusks (clams, oysters, and relatives) that make up most modern shellfish faunas.  Waiparia belong to the family Terebratellidae, which I remember fondly from my undergraduate paleontology labs for their spaceship-like shapes.  These shellfish would have anchored themselves into the seafloor with a holdfast and used their filtering lophophores to collect food particles from the current. I’ve been told that brachiopods are a poor dietary choice, both in terms of nutrients provided and taste.  More familiar and probably more delicious mollusks also lived in the region and are found as fossils in the Kokoamu Greensand.  Scallops are fairly common, and  sea snails and clams were present too.

A cast skull of the extinct squalodont dolphin at the Vanished World Trail visitor center in Duntroon.

Kairuku also had some rather unwelcome neighbors.  Among these were many species of sharks, the grandest of which was Carcharodon angustidensThis species was a relative of the Great White Shark and reached about 9m (27 feet) in length.  Such predators would have been dangerous even to fully grown Kairuku penguins.  Another predatory group was the Squalodontia, an extinct family of shark-toothed dolphins.  Unlike the conical teeth of living dolphins, squalodonts had serrated teeth, with multiple small cusps along the edges.  Waipatiidae were another interesting fossil group of predatory dolphins.  One of the amzing things about the species Waipatia maerewhenua is its procumbant incisors.  These front teeth point forward from the snout, rather than pointing down like the teeth of a normal dolphin.  You can see an artist reconstruction of a beached Waipatia maerewhenua in the background of the Kairuku waitaki artwork that accompanied our paper by scrolling down. This dolphin was not huge like Carcharodon angustidens, but was probably dangerous to at least juvenile Kairuku penguins as well as smaller contemporary penguin species like Duntroonornis parvus.  You an read more about this amazing fossil dolphin and other New Zealand fossils at the University of Otago Geology Museum’s website.

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Written by Dan Ksepka

March 20, 2012 at 6:09 pm

Posted in Uncategorized

8 Responses

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  1. its amazing that there was an animal as smart as a dolphin and as dangeros as a shark!!! Could a Kairuku penguin fight it? also, why does a brachiopod have less nutrents?

    keci

    March 20, 2012 at 7:00 pm

    • Just for the record that particular skull you have posted here is not Waipatia, but an undescribed Squalodon found in the same formation. The Waipatia skull is in the case you can see in the background of your photo.

      Sorry to nitpick. I’ve just been working on a palaeo-art reconstruction of this Squalodon a few years now for Ewan to use when he hopefully publishes it.

      In good news my current draft of the whale piece includes Penguins that could be Kairuku. I finished this draft a week before you guys published, but I’d like to correct those guys to match Kairiku as a tribute to Andrew. You can see the current draft here http://cdylke.blogspot.com/2012/03/squalodon-orca-of-oligocene-2012.html

      Cheers

      Craig

      Craig Dylke

      March 20, 2012 at 7:59 pm

      • Thanks for the save Craig, I’ve corrected the caption. When your final reconstruction is ready, let me know and we will spread the word here!

        Dan Ksepka

        March 21, 2012 at 11:57 am

    • There is no fossil evidence of a battle between these dolphins and a Kairuku penguin, but we suspect a large penguin would have a good chance at escaping and perhaps could get in a few beak strikes to discourage predators. As for brachiopods, there is less edible animal in the shell. A lot of the shell is occupied by the filtering lophophore, whereas clams have more muscles for opening and closing the shell. So, predators get more energy by gobbling down a clam than a same-sized brachipod. You can read more about the differences here: http://invertpaleo.blogspot.com/2011/07/brachiopods-versus-bivalves.html

      Dan Ksepka

      March 21, 2012 at 12:02 pm

      • coooooooooooooollllllllllllllllllllllll

        keci

        March 23, 2012 at 11:49 am

  2. Hey Dan,

    What do you make of the distinctive pits in the bones of the Kairuku holotype and referred specimens? I noticed them first in the published paper, but after arriving here at Otago I noticed just how ubiqituous they are on the Kairuku specimens in person.

    That being said, there seems to be a lot of strange taphonomic damage to nearly everything I’ve seen in the last couple weeks from the Kokoamu Greensand, including the eomysticetids I’ll be studying. I have yet to ask Ewan about the taphonomic features of Kairuku, but just wanted to gauge your thoughts. Otherwise, Ewan pulled me into his office yesterday briefly to show my the Kaiika and Waimanu holotypes… very pretty. Congratulations on getting Kairuku published!

    Bobby

    March 21, 2012 at 4:27 pm

    • I am not an expert on trace fossils but I assume some type of invertebrate is scarping/boring into the bone to obtain nutrients. It would certainly be interesting to know the ichnospecies.

      Dan Ksepka

      March 21, 2012 at 5:00 pm

      • There very well may be some ichnospecies named for similar defects on mollusks – but from my taphonomic research I’ve only come across these a couple times on vertebrate remains, and they are largely unstudied. That being said, very similar traces have been identified on modern human bones trawled from the seafloor in the gulf of Maine, and called “crater defects”, but the taphonomic agent has not even been identified for these modern specimens, and they have only been discussed briefly in one book chapter (Sorg et al. 1997).

        Sorg, M. H., J. H. Dearborn, E. I. Monahan, H. F. Ryan, K. G. Sweeney, and E. David.
        1997. Forensic taphonomy in marine contexts. In W. D. Haglund, and M. H. Sorg, eds.
        Forensic Taphonomy: the Post-Mortem Fate of Human Remains. CRC Press, Boca
        Raton, Florida.

        Bobby

        March 22, 2012 at 2:09 am


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