Wednesday, 31 August 2016

A Transitional Pterodactyl!

Cranial endocast and comparison of brain anatomy in pterosaurs.
(A, B), Volume-rendered CT-based reconstruction of the braincase of the holotype of Allkaruen koi, in dorsal (A) and left lateral (B) views (the bone is rendered semitransparent to show the cranial endocast and the inner ear). (C–H), schematic drawings of brain anatomy in Rhamphorhynchus (C, F), Allkaruen (D, G), and Anhanguera (E, H) in dorsal (C–E) and lateral (F–H) views. Colors (C–H) indicate equivalent brain regions (blue, cerebrum; green, optic lobe; yellow, cerebellum; red, floccular process of cerebellum; pink, semicircular canals). The horizontal black line shows the relationship between the dorsal expansion of the anterior semicircular canal and the forebrain. Abbreviations: asc, anterior semicircular canal; cer, cerebral hemisphere; de, dorsal expansion; f, frontal; floc, floccular process of cerebellum; lab, labyrinth of inner ear; lsc, lateral semicircular canal; lag, lagena; ob, olfactory bulb; oc, occipital condyle; ol, optic lobe; pbt, basipterygoid process; pit, pituitary body; psc, posterior semicircular canal; sc, sagittal crest. Roman numerals indicate cranial nerves. Brain anatomy of Rhamphorhynchus and Anhanguera modified from Witmer et al. (2003). Scale bars are 10 mm.
A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium [PeerJ]

It's always rewarding to watch creationists try to cope with something they claim shouldn't be there when it quite clearly is there and can be seen to be there. One thing they can't do however is admit reality because reality is the one thing that undermines their evidence-free and reality-denying dogma.

There shouldn't be any transitional fossils because transitional fossils show evolution so, so the 'reasoning' seems to go, all those transitional fossils can't be there because evolution doesn't happen. So, this latest discovery of a transitional fossil between two different orders of aerial reptile will need to be explained away somehow.

News of the discovery was published in a press release by the online journal PeerJ:

Scientists today announced the discovery of a new species of pterosaur from the Patagonia region of South America. The cranial remains were in an excellent state of preservation and belonged to a new species of pterosaur from the Early Jurassic. The researchers have named this new species ‘ Allkauren koi’ from the native Tehuelche word ‘all’ for ‘brain’, and ‘karuen’ for ‘ancient’.

Pterosaurs are an extinct group of flying reptiles that lived during most of the Mesozoic Era. This group had an extraordinary adaptation to flight, including pneumatic bones to lighten its weight, and an elongated digit supporting a wing membrane. However, pterosaur neuroanatomy is known from only a few three dimensionally preserved remains and, until now, there was no information on the intermediate forms. This study therefore provides new information on the origin, tempo and mode of evolution in this particular group of flying
reptiles.

The fossil of Allkaruen koi was found in northern central Chubut Province, Patagonia Argentina and the remains included a superbly preserved and uncrushed braincase. In order to study the neurocranial anatomy, researchers used computed tomography to observe, in three dimensions, the cranial endocast and the inner ear. Subsequently, a comprehensive
phylogenetic analysis of the group was performed, including these cranial data and other anatomical features. “Allkaruen, from the middle lower jurassic limit, shows an intermediate state in the brain evolution of pterosaurs and their adaptations to the aerial environment”, said Dr Diego Pol, who is part of the research team. “As a result, this research makes an important contribution to the understanding of the evolution of all of pterosaurs.”

The importance of this find is that it fills in a gap in our knowledge of the evolution of the pterosaurs and in particular the neuroanatomical changes probably related to improved flying ability and different life-styles between them and the related but distinct rhamphorhyncoids. In other words it shows distinctly intermediate and transitional features between these two groups. Note: this is not just a transition from an earlier to a later species within the same genus or order but between two related orders.

Abstract

Pterosaurs are an extinct group of highly modified flying reptiles that thrived during the Mesozoic. This group has unique and remarkable skeletal adaptations to powered flight, including pneumatic bones and an elongate digit IV supporting a wing-membrane. Two major body plans have traditionally been recognized: the primitive, primarily long-tailed paraphyletic “rhamphorhynchoids” (preferably currently recognized as non-pterodactyloids) and the derived short-tailed pterodactyloids. These two groups differ considerably in their general anatomy and also exhibit a remarkably different neuroanatomy and inferred head posture, which has been linked to different lifestyles and behaviours and improved flying capabilities in these reptiles. Pterosaur neuroanatomy, is known from just a few three-dimensionally preserved braincases of non-pterodactyloids (as Rhamphorhynchidae) and pterodactyloids, between which there is a large morphological gap. Here we report on a new Jurassic pterosaur from Argentina, Allkaruen koi gen. et sp. nov., remains of which include a superbly preserved, uncrushed braincase that sheds light on the origins of the highly derived neuroanatomy of pterodactyloids and their close relatives. A µCT ray-generated virtual endocast shows that the new pterosaur exhibits a mosaic of plesiomorphic and derived traits of the inner ear and neuroanatomy that fills an important gap between those of non-monofenestratan breviquartossans (Rhamphorhynchidae) and derived pterodactyloids. These results suggest that, while modularity may play an important role at one anatomical level, at a finer level the evolution of structures within a module may follow a mosaic pattern.

Codorniú L, Paulina Carabajal A, Pol D, Unwin D, Rauhut OWM. (2016)
A Jurassic pterosaur from Patagonia and the origin of the pterodactyloid neurocranium.
PeerJ
4:e2311 https://doi.org/10.7717/peerj.2311

Open Access

Even using the wooly and hopelessly inadequate 'kind' that the authors of the Bible tried to fit living things into, this find represents a major challenge to creationists, so the most likely response will be to ignore it altogether and fall back on the nonsensical 'your evidence can't beat my faith!' excuse. It is as embarrassing for the creation industry and their dupes as the discovery of tiktaalik or the discovery of an intermediate between lizards and snakes was. This find shows unmistakable evidence that the more advanced pterodactyloids evolved from the more primitive rhamphorhyncoids and is very clearly an intermediate species between these two groups of aerial reptiles.

But, if perchance a serious creationist feels able to cope with this and explain how it fits in with biblical creationism, then feel free to outline this below...

Oh! I'd also be interested in how this paper and the discovery described in it show evidence that the Theory of Evolution is a theory in crisis which biologists are rapidly losing confidence in and which is about to be replaced by magic done by an invisible skyman (or intelligent (sic) design) as the best available explanation of Earth's biodiversity.

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2 comments :

  1. paraphyletic rhamphorhynchoids.....pterodactyloids.....non-monofenestratan breviquartossans

    I suspect these creatures became extinct out of sheer frustration at trying to spell their own names.

    Seriously, it's fascinating what we can deduce about such subtle aspects of evolution that happened so long ago. The creationist stories are not only hopelessly wrong, but trite and dull by comparison.

    ReplyDelete
    Replies
    1. Absolutely! I've always found the 'God did it all by magic' explanation profoundly unsatisfactory and dismissive of nature. Almost a betrayal of it by trying to reduce it all to something easy to explain away with little or no thought. Even if I believed in a creator I think I would try to credit it with a bit more imagination and creativity. It sometimes seems that creationists are insisting their god be a small god so they don't need to work very hard to understand things - it's all ineffable magic!

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