Tag: fossil

Australian Megafauna A-Z: C is for Centropus

Posted on by Travis Park in Australian Megafauna A-Z, Australian palaeo, Aves, CAVEPS

Time for another entry in my Australian megafauna A-Z series. We’ve previously looked at Alkwertatherium and Barawertornis. Both these taxa have come from the north of the continent, so I think it’s only fair we give some attention to fossils from the southern end of the continent this time around. This fossil bird species was found in a cave in the south-eastern corner of South Australia. Ladies and Gentlemen, C is for Centropus colossus, better known as the giant coucal.

Coucals are closely related to cuckoos and roadrunners (it’s a real bird not just a cartoon). They are also related to the enigmatic South American bird the hoatzin, although exact relationships are still being debated. This makes the group one of the earlier diverging lineages of modern birds (Edit: thanks to David in the comments and also me going and doing some further reading, coucals are not closely related to the hoatzin. Moral of the story, check your sources! Thanks for the heads up David!). Today in Australia there is one living species of coucal, the pheasant coucal. However, this taxon only lives in the northern forests of Australia and when the fossil species was found in the late seventies, it came as a bit of a surprise to discover this group so far south.

This is the pheasant coucal (Centropus phasianinus), the only living australian coucal species. Image source: Wikipedia.
This is the pheasant coucal (Centropus phasianinus), the only living australian coucal species. Image source: Wikipedia.

Centropus colossus was described based on an almost complete left humerus by Robert Baird in 1985. Its reduced muscle attachment points on the pectoral crest of the humerus suggest that it was flightless. Modern coucals only fly when disturbed, but the giant coucal was a third larger in size than the pheasant coucal and may therefore have been completely flightless. The presence of the giant coucal in what is today relatively arid country suggests that in the past this region had much more plant cover.

A similar issue has arisen with the discovery of fossil coucal remains from the Thylacoleo Caves in the Nullarbor Plain, south-central Australia. These remains, which are from an undescribed species of coucal were discussed in a talk at CAVEPS 2013 (the conference I recently attended, see here for my quick round up of the week) by Flinders University PhD student Elen Shute (also see this article for further info). The presence of the coucal indicates that this region was thickly covered in vegetation in the past, despite it being desert at present.

A reconstruction of the giant coucal (Centropus colossus) feeding on a small lizard just in front of the sink hole whereits fossils where found. Image by Frank Knight, from Kadimakara.
A reconstruction of the giant coucal (Centropus colossus) feeding on a small lizard just in front of the sink hole whereits fossils where found. Image by Frank Knight, from Kadimakara.

The generic name, Centropus, comes from two Latin words; centro, meaning spine and pus, meaning foot. This is referring to the characteristic elongate nail on the hallux of other taxa in the genus. The specific name refers to the fact that this species is larger than other taxa of this genus.

Well that’s C done, D will be a slightly better known animal, if not the best known of all the Australian megafauna. All will be revealed in the near future…

References

Baird, Robert F., 1985. Avian fossils from Quaternary deposits in ‘Green Waterhole Cave’, south-eastern South Australia. Records of the Australian Museum 37(6): 353–370.

Baird, R.J.F. 1985. Centropus colossus Baird 1985, The Giant Coucal, Pp. 205–208 in Vickers-Rich P., and Van Tets, G.F. (eds), Kadimakara, Extinct Vertebrates of Australia. Princeton University Press: New Jersey. 284 pp.

Clode, D. 2009. Prehistoric giants, the megafauna of Australia. Museum Victoria Nature Series, Melbourne, 72 pp.

Other posts in the Australian Megafauna A-Z series:

A is for Alkwertatherium

B is Barawertornis

Dugong it, where are all the Australasian fossil sea cows?

Posted on by Travis Park in Australian palaeo, Fossil mammals, Marine mammals

Well, time certainly flies when you’re busy and before you know it, it’s been almost a month since you’ve last written a blog post. At least that’s what has just happened to me! I’ve been busy doing research on fossil whales, fossil penguins, talking fossil penguins at Museum Victoria’s latest SmartBar, giving a talk on Australian fossil seabirds as well as preparing and submitting abstracts for an upcoming conference, whew! But I haven’t been blogging and bringing you, dear readers, new and cool fossil discoveries. So let’s rectify that situation then shall we?

As you may have guessed from the title above, this post is about fossil dugongs, or more precisely, the lack of them in the Indopacific region. Whilst today the region is the centre of sirenian abundance and fossils are known from areas such as Madagascar, Somalia, India, Sri Lanka and Indonesia, fossil evidence from the Indopacific has been lacking with the only reported finds being a partial mandible from the Pliocene of South Australia, a partial rib from the Miocene-Pliocene boundary of Victoria and fossils of the extant Dugong dugon from the Quaternary of Papua New Guinea and Holocene of southeast Australia. There is no clear explanation for the scarcity of dugong fossils in the Indopacific region as the find from South Australia shows they were present in the area in the past. Furthermore, there are plenty of available outcrops of sediments of the correct age, the sediments also indicate the climate would have been suitable for dugongs to be present and the high densities of sirenian bones make them favourable for preservation.  Therefore any new finds would be crucial to gaining a more detailed understanding of sirenian evolution in the Indopacific.

The single living species of dugong, Dugong dugong (that's a lot of dugongs for one sentence). Image source habitatadvocate.com.au.
The single living species of dugong, Dugong dugon (that’s a lot of dugongs for one sentence). Image source habitatadvocate.com.au.

One such find was made but it was actually 30 years ago, with the fossils not being studied until only recently and published in the Journal of Vertebrate Paleontology this July by Erich Fitzgerald (who also happens to be one of my PhD supervisors) and colleagues from the Smithsonian, Howard University College of Medicine and Flinders University. The recovery of the fossils (consisting of three posterior vertebrae, one anterior caudal vertebra and seven partial ribs) is a story in itself. The fossils were found in a cave in the remote Hindenburg Range of the New Guinea Highlands, Papua New Guinea, but when the fossils were being recovered the cave suddenly flooded meaning the crew had to make a quick exit leaving some fossil material behind!

Some of the vertebrae of the fossil seacow found in Papua New Guinea, being held by lead author Dr. Erich Fitzgerald. Image source MV.
Some of the vertebrae of the fossil seacow found in Papua New Guinea, being held by lead author Dr. Erich Fitzgerald. Image source MV.

The fossils date to between 11.8–17.5 Ma, giving a minimum age of just before 12 Ma for sirenians being present in Australasian coastal marine ecosystems, and by implication their primary food source: seagrasses. As Dr. Fitzgerald explains, “Modern-day dugongs are major consumers of sea-grass, and, by doing so, have a tremendous impact on the structure of the ecosystem,” said Dr Fitzgerald. “They participate in a delicate balancing act: their feeding allows diversity in sea-grass and animal species that would otherwise be lacking. Previously, it was thought that sea cows were fairly new arrivals in Australasia, and that their relationship with sea-grass ecosystems here was a recent event. This new evidence suggests sea cows have been an important component of Australasia’s marine ecosystems for at least 12 million years and that their role in the long-term health of these environments may be substantial.”

So whilst we are still in the dark about an awful lot of the history of sirenians in Australasia, this new find does shed a little light their evolution and now we know that they were there around 12 Ma, researchers can start looking in shallow marine sediments of similar age to find the next illuminating discovery.

Dr. Fitzgerald’s comments are taken from the Museum Victoria media release.

Reference

Erich M. G. Fitzgerald, Jorge Velez-Juarbe & Roderick T. Wells (2013) Miocene sea cow (Sirenia) from Papua New Guinea sheds light on sirenian evolution in the Indo-Pacific. Journal of Vertebrate Paleontology 33: 956–963.

Where haramiyid?

Posted on by Travis Park in China palaeo, Fossil mammals

Most people would class the Cenozoic (the period of time spanning from 66 Ma to the present) as the Age of Mammals. Certainly the diversity of mammals exploded and the majority of modern groups evolved after the demise of the non-avian dinosaurs at the end of the Cretaceous. However, what a lot of people don’t realise when they think about mammals is that they have been around for a lot longer than 66 Ma. The oldest known definite mammals date to around 165 Ma but the actual origins of the group would have been some time previous to that but remains uncertain, primarily due to the fact that most early mammals are known only from isolated teeth.

Two remarkable new finds, both from the Middle – Late Jurassic Tiaojishan Formation in the Hebei Province of China, have provided new food for thought in this debate, whilst not necessarily providing any definitive answers. The two new species, described in separate papers in last week’s issue of Nature preserve not only teeth, but skull material and post-cranial elements such as vertebrae, limb bones and even fur. Both species belong to an extinct group of mammals known as the haramiyids.

Artists reconstructions of Arboroharamiya (l) and Megaconus (r). Art by Zhao Chuang (l) & April Isch (r).
Artists reconstructions of Arboroharamiya (l) and Megaconus (r). Art by Zhao Chuang (l) & April Isch (r).

The first new species, Arboroharamiya jenkinsi, described by Zheng et al., was an omnivore or herbivore that had several adaptations for living in trees, such as elongated digits. The morphology of its caudal (tail) vertebrae also hints at it possessing a prehensile tail. It has been dated to 160 Ma.

The holotype specimen of Arboroharamiya jenkinsi, with a line drawing indicating the locations of the elements. From Zheng et al. 2013.
The holotype specimen of Arboroharamiya jenkinsi, with a line drawing indicating the positions of skeletal elements. From Zheng et al. 2013.

The second new species, Megaconus mammmaliaformis, described by Zhou et al., was herbivore that lived on the ground, with its morphology indicating it had an ambulatory (walking) gait similar to that of a modern day armadillo. Megaconus was more primitive than Arboroharamiya and is also slightly older, dating to around 164 – 165 Ma.

a, skeletal redconstruction of Megaconus. b, the holotype specimen of Megaconus mammaliaformis. c, line drawing indicating position of skeletal elements. From Zhou et al. 2013.
a, skeletal redconstruction of Megaconus. b, the holotype specimen of Megaconus mammaliaformis. c, line drawing indicating position of skeletal elements. From Zhou et al. 2013.

Now, so far so good. But where these two studies provide conflicting opinions about the early mammal evolution is in their phylogenetic analyses. The Zheng et al. paper groups Arboroharamiya and all other haramiyids as the sister group to the multituberculates within Mammalia. This puts the origin of mammals at around 215 Ma, in the Late Triassic, much older than most palaeontologists would estimate, but in agreement with molecular estimates. The Zhou et al. paper on the other hand, placed Megaconus and all other haramiyids outside of Mammalia, meaning they are not closely related to multituberculates and also estimates the origin of mammals at around 180 Ma, a figure more in line with palaeontologists expectations given what fossils are currently known.

a, the phylogeny reached by Zhengh et al. b, the phylogeny reached by Zhou et al. you can see the origin date of mammals and the position of the haramiyids differs in the two phylogenies. From Cifelli & Davis, 2013.
In this simplified version of the phlylogenies produced by Zheng at al. and Zhou et al., you can see the origin date of mammals and the position of the haramiyids differs in the two phylogenies. From Cifelli & Davis, 2013.

So, which tree is the correct one? Well, neither probably. There are several factors why this will most likely turn out to be the case. One is that these two phylogenies don’t contain the other new species, a potential next move for the authors of these two papers is to combine their data a produce a phylogeny with both new taxa to see where the haramiyids place. Another is that although these fossils are relatively well preserved, there is still a lot of anatomical and morphological data missing from them, with Arboroharamiya possessing less than a quarter of the 436 characters used in the Zheng et al. study and Megaconus possessing less than half of the 475 characters used in the Zhou et al. study. A third factor is that whilst these two new taxa might be relatively well preserved, the majority of other early mammal taxa are poorly preserved or are only known from teeth. More fossils of the quality of these two new specimens would help resolve the origin of the mammals.

Finally, there is also a little lesson to be learnt here about cladistics, the method by which phylogenies are now generated. Whilst this method is undoubtedly the best and most powerful tool we possess for distinguishing relationships between species at present, there are many different cladistic techniques that scientists can employ, and it will often depend which technique is used as to which phylogeny they end up obtaining. So don’t always accept the phylogenetic position of taxa just because there’s a phylogeny showing it that way, try to look at what methods they’ve used to obtain their results. Remember, good scientists will question everything!

References

Cifelli, R. L. & Davis, B. M. 2013. Jurassic fossils and mammalian antiquity. Nature 500, 160–161.

Zheng, X., Bi, S., Wang, X. & Meng, J. 2013. A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period. Nature 500, 199–202.

Zhou, C.-F., Wu, S., Martin, T. & Luo, Z.-X. 2013. A Jurassic mammaliaform and the earliest mammalian evolutionary adaptations. Nature 500, 163–167.

Research/Conference trip to New Zealand: Dunedin

Posted on by Travis Park in Cetacean research, New Zealand palaeo, Personal research

After an exciting end to my time in Christchurch I thought Dunedin might be the destination for a more relaxing few days. However the excitement began on the drive down to Dunedin! I was given a lift by Dr. Alan Tennyson, Curator of Vertebrates at Te Papa Museum in Wellington. On the way south from Christchurch we decided to take slight detour and head to Haugh’s quarry in the Hakataramea Valley to have a brief look around to see if we could spot any fossils. We spent about 90 minutes looking around and were about to get back in the truck to continue on to Dunedin when Alan said “let’s have a quick look around the top of the quarry”. We searched around there for a few minutes until Alan found a bit of bone exposed. We brushed a bit of sediment away, the bone kept going. We brushed more sediment away, the bone still kept going! After a few minutes more it became apparent that this was a seriously large animal, we had bone spread out along at least a two metre long strip and there was no sign of the end of it! It was a fossil whale of some description, though what exactly remains to be seen. We realised that we were not going to be able to excavate this fossil ourselves and we were already going to be late for the beginning of the conference, so we decided to take some photos of what we had uncovered and head on to Dunedin.

This is Haugh's Quarry where Alan discovered the fossil whale. It was discovered pretty much were this photo was taken from. Photo by author.
This is Haugh’s Quarry where Alan Tennyson discovered the fossil whale. It was discovered pretty much where this photo was taken from. Photo by the author.

The next day we showed the images to Professor Ewan Fordyce, head of the Geology department at University of Otago and world-renowned authority on fossil whales. He was intrigued enough to want to go and excavate the fossil on Wednesday but then he received a phone call that two whales (Arnoux’s beaked whale or Berardius arnuxii) had stranded near Bluff, at the southern end of the island. He then invited me to come along on Wednesday and help dissect one of them! So I spent Wednesday covered in blood, guts and (when I helped to move the head) brains! Great fun!

Yours truly looking very CSI-esque at the Berardius dissection. Photo by Maria Zammit.
Yours truly looking very CSI-esque at the Berardius dissection. Photo by Maria Zammit.

When I wasn’t helping discover fossil whales or dissect dead extant ones, I also attended a few of the talks at the conference. Unfortunately there wasn’t as many palaeontology related talks as I had hoped, but it was more than made up for by the amount of research and field trips I got to go on. I managed to get lots of photos of the collections at University of Otago and Otago Museum. I also met a lot of new colleagues and (I hope) friends, one of whom, Bobby Boessenecker, has one of the best palaeontology blogs going.

Dunedin is a beautiful little city and is definitely worth a visit if the opportunity presents itself.

Slightly less gory than the previous picture, this is the Clocktower building at University of Otago, Dunedin. An example of how nice a city it is. Photo by the author.
Slightly less gory than the previous picture, this is the Clocktower building at University of Otago, Dunedin. An example of how nice a city it is. Photo by the author.

A big thank you goes to Ewan Fordyce for allowing access to his collections, taking time out of his busy schedule to talk with me and of course for letting me join in on the whale dissection.

Another big thank you goes to Alan Tennyson for driving me around everywhere as well as several interesting discussions.

And a massive thank you goes to Felix and Ikerne for letting me stay with them for the week, I look forward to returning the favour one day in Melbourne!

A great trip and I look froward to returning to New Zealand as soon as possible.