The Earth Story

A Snapshot in Time part 2 - The Daohugou Biota

In the first post of this pair (see: http://tmblr.co/Zyv2Js1lLwcex) we discussed the Jehol formation in China, the best example of an early Cretaceous environment, preserved like Pompeii by a series of volcanic eruptions pushing dead animals into lakes and burying them in the ash that fossilised them.

While argument rages over the connections between the organisms from these two lake sediment sequences, separated by a crucial 30 million years in time during which birds separated from dinosaurs (amongst other significant events), they do occupy the same stratigraphic column, and had similar conditions of deposition, fossilisation and preservation. However researchers can't agree yet on which species characterises which biota, nor on where the line between them lies (see the saga of lumpers and splitters at http://on.fb.me/1PpsZnU)

Deposited during an interval spanning roughly 164-158 million years back, it is made up of lake sediments interspersed with volcanic rocks from pyroclastic flows, much like the Jehol formation. Unlike the latter, it has been folded and mixed up by erosion and volcanic activity, testifying to more active tectonics than when the later beds were deposited in similar geographic settings. There has been some controversy over their actual age, though most agree on the window quoted above using arguments from biostratigraphy (where fossils are in the stack) shows the rocks to be earlier. The latest radioactive dates also support the accepted window. Like the Jehol many soft tissues, fur, feathers and others have been perfectly preserved by the fine grained ash.

Many early mammals have been found here, including early aquatic creatures and the first gliding squirrel type critter. The trees included conifers and ginkoes. The earliest birds were just recently found here, as researcher hoped, giving a glimpse into their first days on Earth, just after their divergence from dinosaurs (the subject of my third upcoming post).

Together these two formations make up the only detailed record of a land ecosystem of this period anywhere, and their unique nature promises many exciting discoveries in the future. More new creatures will turn up, and the comparison between these two excellently preserved and similar ecosystems geologically 'photographed 30 million years apart in time will reveal many new insights into evolution at one of its critical phases for several major clades.

Loz

Image credit: Graphic: Julia Molnar Salamander Chunerpeton: Sullivan et al, referenced below Sinornithosaurus: Dave_NGMC91 Graphic 2, the early mammal Castorocauda: Nobu Tamura http://bit.ly/1zMUki0 http://bit.ly/1hJIgl7 http://bit.ly/1Pp4Yx5

The Mesozoic Park: Yi qi

Common name: Batdino Size: Pigeon sized (10cm). Age: Mid Jurassic (160 million years ago) Geographic range: China/Mongolia. Liked: Flying/gliding. Disliked: Being eaten. Taxonomy: Animalia > Chordata > Dinosauria > Theropoda>Scansoriopterygidae>Yi>qi

The Jehol and Daohugou Biota of north eastern China (see http://on.fb.me/1cViPit and http://on.fb.me/1Hnu8YF) have repeatedly stunned palaeontologists over the last couple of decades with their well preserved 160 and 130 million year old ecosystems. The time period covered by the two formations spanned the transition between feathered dinosaurs and birds, amongst other things, and the exceptional preservation of these fossilised organisms has brought us many feathers, mammalian fur and other rarities to study that are usually not preserved in fossilisation.

Yi qi comes from the older rocks of the Daohugou formation, some 160 million years old. These are the remnants of tree shaded lakes that were periodically covered in huge volumes of volcanic ash from pyroclastic flows, each killing a wide diversity of animals and shunting them into the lake beds, where the fine grained ash preserved them in near perfect detail. Only one geologically flattened partial specimen exists, the size of a medium bird that was maybe a tree dweller. The name comes from the Chinese for 'strange wing'.

Several features of its anatomy are unique. Its elongated third finger had a membrane of sliding skin and a never before seen long bony strut attached at the wrist, resulting in a bat shaped wing arrangement. Whether a newly evolved wrist bone or a ossified cartilage, the feature is very odd. The critter was a feathered therepod, whose plumes resembled quills or paintbrushes ( for an idea of what these dino feathers looked like, see my past posts of them preserved in amber, Jurassic park style, at http://on.fb.me/1DTZQdF and http://on.fb.me/1QpTFac). They were covered all over and quite dense, up to 6 cm long. Some of the bat like membrane was also preserved, and no flight feathers were present. They analysed the melanosomes for colour and found the feathers were black like a crow's and brown on the head.

The resemblance to a bat would be an example of convergent evolution, where different animals from widely varied evolutionary backgrounds take on a similar shape, such as tuna fish, dolphins (mammals) and ichthyosaurs (reptiles). It also suggests that flight evolved several times using different means in the dinosaurian and early bird lineages with maybe several groups transitioning from gliding to powered flight. It is also a transitional form between feathered dinos evolving into birds and the unrelated pterosaurs, with their more bat like wing structures. This is certainly an interesting and unusual twig on the great tree of expressed nucleic acids that we call life, and, incidentally, the dinosaur with the shortest name of all.

Loz

This article is a part of our "Mesozoic Park" series that is leading up to the release of Jurassic World. For more information, please see our introductory post at: http://on.fb.me/1ELwHW5 or if you already know about the series but missed a few articles you can find links to the first 10 posts at "Update #1," here: http://on.fb.me/1ED1tOH and "Update #2" here: http://on.fb.me/1AsdbPx

Image credit: graphic Dinostar Co. Ltd., photos Zang Hailong http://bit.ly/1EYblI0 http://bit.ly/1EDJFq6 http://bit.ly/1GI1QNp http://bit.ly/1GwyNXL

Original paper, open access: http://bit.ly/1GQCsoQ

The Mesozoic Park: A Snapshot in Time part 2 - The Daohugou Biota

In the first post of this pair (see: http://tmblr.co/Zyv2Js1lLwcex) we discussed the Jehol formation in China, the best example of an early Cretaceous environment, preserved like Pompeii by a series of volcanic eruptions pushing dead animals into lakes and burying them in the ash that fossilised them.

While argument rages over the connections between the organisms from these two lake sediment sequences, separated by a crucial 30 million years in time during which birds separated from dinosaurs (amongst other significant events), they do occupy the same stratigraphic column, and had similar conditions of deposition, fossilisation and preservation. However researchers can't agree yet on which species characterises which biota, nor on where the line between them lies (see the saga of lumpers and splitters at http://on.fb.me/1PpsZnU)

Deposited during an interval spanning roughly 164-158 million years back, it is made up of lake sediments interspersed with volcanic rocks from pyroclastic flows, much like the Jehol formation. Unlike the latter, it has been folded and mixed up by erosion and volcanic activity, testifying to more active tectonics than when the later beds were deposited in similar geographic settings. There has been some controversy over their actual age, though most agree on the window quoted above using arguments from biostratigraphy (where fossils are in the stack) shows the rocks to be earlier. The latest radioactive dates also support the accepted window. Like the Jehol many soft tissues, fur, feathers and others have been perfectly preserved by the fine grained ash.

Many early mammals have been found here, including early aquatic creatures and the first gliding squirrel type critter. The trees included conifers and ginkoes. The earliest birds were just recently found here, as researcher hoped, giving a glimpse into their first days on Earth, just after their divergence from dinosaurs (the subject of my third upcoming post).

Together these two formations make up the only detailed record of a land ecosystem of this period anywhere, and their unique nature promises many exciting discoveries in the future. More new creatures will turn up, and the comparison between these two excellently preserved and similar ecosystems geologically 'photographed 30 million years apart in time will reveal many new insights into evolution at one of its critical phases for several major clades.

Loz

This article is a part of our "Mesozoic Park" series that is leading up to the release of Jurassic World. For more information, please see our introductory post at: http://on.fb.me/1ELwHW5 or if you already know about the series but missed a few articles you can find links to the first 10 posts at "Update #1," here: http://on.fb.me/1ED1tOH

Image credit: Graphic: Julia Molnar Salamander Chunerpeton: Sullivan et al, referenced below Sinornithosaurus: Dave_NGMC91 Graphic 2, the early mammal Castorocauda: Nobu Tamura http://bit.ly/1zMUki0 http://bit.ly/1hJIgl7 http://bit.ly/1Pp4Yx5 Original paper free access http://bit.ly/1KM9zc2 Paper paywall access: http://bit.ly/1zBJqeO