Tag: giant

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

The Giant Turtle That Really Sucked

Posted on by Travis Park in Marine reptiles, Turtles

Turtles are an underappreciated group of tetrapods. Despite a brief flirtation with popular culture in the late eighties and early nineties (although no known species actually eats pizza and wields ninja weapons), the shelled reptiles still don’t get the attention their seriously weird morphology deserves.

The oldest known turtles are from the Late Triassic of China (Li et al. 2008), but the debate still rages on regarding which group turtles actually evolved from, so derived is their morphology (Carroll 2013). There are around 300 living species of turtle, divided into 14 families, the largest of which is the marine leatherback turtle, which can reach 2m in length. Yet this pales in comparison with the largest known fossil turtle, Archelon ischyros, which had a shell over 4 m long! Yet for all of the turtles of different shapes and sizes, none have ever been found like the new species described in a paper published in PLoS One last week.

Here you can clearly see just how huge the largest known fossil turtle, Archelon, really was. Image from Moody et al. 2013.
Here you can clearly see just how huge the largest known fossil turtle, Archelon, really was. Image from Moody et al. 2013.

The paper, written by Nathalie Bardet and colleagues, names a new species of giant turtle, Ocepechelon bouyai from the Late Cretaceous (~65 Ma) phosphates of the Oulad Abdoun Basin in Morocco. In it they describe a skull of a turtle that is unlike any other ever known. Most turtles have beaks with horny ridges that they use to slice through their food. Ocepechelon bouyai however used a completely different method. The snout of its skull was shaped like a pipette tube which it used to suck in its prey, a method known as suction feeding. This feeding method is relatively common in aquatic vertebrates such as fish and marine mammals and some living species of turtle do also use this method of feeding, but it is very rarely reported in Mesozoic marine reptiles, let alone to this extreme degree of specialisation and unique morphology.

Here is a reconstruction of the new turtle species, Ocepechelon bouyai. How weird is that skull morphology!? Image from Bardet et al. 2013.
Here is a reconstruction of the new turtle species, Ocepechelon bouyai. How weird is that snout!? Image from Bardet et al. 2013.

In an unlikely example of convergent evolution (where two separately related taxa evolve similar features), the authors compare this strange animal to modern beaked whales. These marine mammals also possess a long toothless rostrum that they open rapidly to suck in prey. This convergence also extends to other parts of the skull, the nostrils are situated further towards the back of the top of the skull (or posterodorsally if you prefer) and also the squamosals are very well developed like in beaked whales, these would have allowed the attachment of strong throat muscles to help generate the large suction forces necessary for this mode of feeding.

Here's the holotype skull of Ocepechelon bouyai. You can see the elongated, toothless rostrum and enlarged squamosals that make the authors compare it to a beaked whale. Image from Bardet et al. 2013.
Here’s the holotype skull of Ocepechelon bouyai. You can see the elongated, toothless rostrum and enlarged squamosals that make the authors compare it to a beaked whale. Image from Bardet et al. 2013.

This find shows that at the end of the Cretaceous, the shallow seas where Morocco is today possessed a diversity of animals that is still yet to be fully realised. The pipette like rostrum of O. bouyai is unique among tetrapods and shows that this cool group of animals have plenty more surprises up their sleeves. Cowabunga dudes! Ahem…

References

Bardet N, Jalil N-E, de Lapparent de Broin F, Germain D, Lambert O, et al. (2013) A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods. PLoS ONE 8(7): e63586. doi:10.1371/journal.pone.0063586

Carroll, R. 2013. Problems of the Ancestry of Turtles in D. B. Brinkman et al. (eds.), Morphology and Evolution of Turtles. Springer, New York, 576 p.

Li, C; Wu, XC; Rieppel, O; Wang, LT; Zhao, LJ (November 2008). “An ancestral turtle from the Late Triassic of southwestern China”. Nature 456 (7221): 497–501.

Richard T. J. Moody, Cyril A. Walker, and Sandra D. Chapman. 2013. Fossil European Sea Turtles: A Historical Perspective in D. B. Brinkman et al. (eds.), Morphology and Evolution of Turtles. Springer, New York, 576 p.