Biology Ancient Australia (Extinct Megafauna, Dinosaurs etc)

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I've just recently found out i can volunteer my time online and transcribe botany specimen data sheets from the sa museum so they have a digital record of them, it's very interesting to go through.

Good on you.

 

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This fossil is a beauty, a one in a trillion. Look at the soft tissue preservation. Meet Ptychodos, a 75 myo mackerel shark, from the same family that includes the extinct gigantic shark megalodon and our current great white shark.

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Note - Other than their teeth, sharks preserve poorly because they have no bones. Often paleos will have millions of shark teeth from an animal and that's all. This is truly remarkable.

‘An enigma’: scientists finally learn what giant prehistoric shark looked like

Full and part skeletons found in Mexico reveal body shape and anatomy of Ptychodus as well as its likely diet

www.theguardian.com

 

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I've been watching Peter do this reconstruction of a short faced kangaroo, Simosthenurus occidentalis over the last few months, this is the first time I've seen it placed in a scene. Peter agonised over issues like the dew claw and the shape of the toes, matters which remain uncertain but are resolved by plonking it in a bit of grass.



Paleo's have just released a paper about Simosthenurus occidentalis

‘Unlike anything today’: Gippsland fossil unlocks secrets of kangaroo that died out 46,000 years ago

Abrupt extinction of short-faced kangaroo a reminder to protect the environment, palaeontologists say

www.theguardian.com

I think I have posted about this before, these guys are believed to be walkers rather than hoppers, some have suggested an upright gait like a human, others have suggested a posture more like a bipedal dino. Peter has avoided the issue by posing it in a stationary position.

Added - I remembered I did a 'digital sketch' of it walking in a dino like fashion last year, the neck looks too long. Anyway here it is:

 

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Went to the Adelaide museum today, just seeing the T rex skull cast makes you wonder how crazy the earth was with these magnificent creatures roaming around.

 

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Went to the Adelaide museum today, just seeing the T rex skull cast makes you wonder how crazy the earth was with these magnificent creatures roaming around.

I had a similar feeling seeing the Triceratops MOV has. There was no place for large mammals such as ourselves with T-rex et al running around, lucky that big rock hit.

 

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Totally irrelevant but very nice reconstruction of a typical Ediacaran 'frondomorph' by my friend Peter Trusler to start the post with, these are sessile animals, not plants. The Ediacaran period (691 to 541-mya) saw the rise of the first complex, active, multicellular organisms. These critters were powered by increasing oxygen levels over the previous billion years. Paleos argue about how much of the progressive rise oygen in the preceeding few billion years was biological and how much was geochemical, probably both. This article proposes a novel mechanism for higher oxygen levels occurring in Ediacaran, the loss of Earth's magnetic field about 591 mya.

Collapse of Earth's magnetic field may have fueled evolution of life 600 million years ago

The planet's magnetic field may have collapsed around 600 million years ago, enabling a major oxygenation event and perhaps supercharging evolution.

www.livescience.com

The authors propose the loss of the magnetic field led to increased hydrogen leaking from the upper atmosphere resulting in an increase in available oxygen in the atmosphere and the oceans. This is speculative without any actual proof. The graph below shows atmospheric oxygen over the last billion years, you will note oxygen levels rising in the 40 million years before the loss of the magnetic field.

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Austrophyllolepis was a ‘freshwater’ placoderm from Mt Howitt, Victoria that my friend Peter reconstructed for a paper by IIRC by John Long, quite a long time ago. He sent me a copy because we had been discussing sexual dimorphism in placos. I didn't know he'd done this very nice reconstruction until recently. Note how similar the claspers are to sharks and rays. He's done all the fiddly bits, that OCD demanding ornamentation on the armor. A pretty sophisticated animal, of a reasonable size that clearly didn't mind a bit of hanky panky. Not much has changed over the last 380-400 million years ago. These are an Australian and Antarctic species only.

He was pleased because he'd done the ventral surface in standard fish finish #1 - 'Silvery White', and some years later they had recovered pigments suggesting a number of placos are silvery white below with red/black pigments on top. Counter shading goes back >400 million years.



This is a cast of the top (dorsal) armor of the head and thorax, note how complex ornamentation is. You can see a fin clearly on the left.

 

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Six monotremes feature in these 100 million year old fossils from Lightning Ridge, including the 'Echidnapus'. This is another example of old samples that had never been looked at properly until now.

‘Enormously exciting’ fossils found in NSW opal field suggest Australia had ‘age of monotremes’

Discovery of ‘echidnapus’ and two more species show the furry egg-layers predated marsupials

www.theguardian.com

 

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Not quite extinct, a spotted Quoll. Nice pic. This one is from a protected area in ACT. I've never been lucky enough to see one in the wild, pretty rare on the mainland.

Man's encounter with rare Aussie species: 'Most beautiful creature I've ever photographed'

Not many people have seen the elusive creature which was once extinct on mainland Australia. Find out more.

au.news.yahoo.com

 

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Using a ZooMS (Zooarchaeology by Mass Spectrometry) scientists have gone back to old collections of small, unidentified bone fragments and identified them as various types of North America megafauna. What mighty animals these were, mastodons, saber-toothed tigers, enormous wolves, bison, tall camels and giant beavers. 50,000 years later they were gone.

Clues to mysterious disappearance of North America's large mammals 50,000 years ago found within ancient bone collagen

50,000 years ago, North America was ruled by megafauna. Lumbering mammoths roamed the tundra, while forests were home to towering mastodons, fierce saber-toothed tigers and enormous wolves. Bison and extraordinarily tall camels moved in herds across the continent, while giant beavers plied its...

phys.org

 

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I've posted about Genyornis before, the recent finds included an articulated skull. Nice illustration by one of the authors of the paper gives it a very Dino feel, probably because we cant see the rear two thirds of the beasty. The skull reconstruction is a real beauty.

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The CNN article is easily read, includes a link to the original paper but does include a few US phrases we wouldn't use. https://edition.cnn.com/2024/06/03/science/genyornis-newtoni-skull-thunder-bird-scn/index.html

 

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Another newly described Australian pterosaur, Haliskia peterseni. 100 million years ago the Eromunga sea was a popular location if you were a pterosaurs. This one is 22% complete, which is a lot for pterosaur.

100-million-year-old fossil find reveals huge flying reptile that patrolled Australia’s inland sea

In 2021 a former avocado farmer discovered the most complete pterosaur skeleton ever found in Australia – and new research shows it represents a previously unknown species.

theconversation.com

My friend Peter is currently doing a reconstruction of one of our pterosaurs (forgotten which), the fossils tell an amazing story, the pterosaur has has been grabbed by an ichthyosaur. which in turn is bitten in half by a massive Kronosaur.

 

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Another newly described Australian pterosaur, Haliskia peterseni. 100 million years ago the Eromunga sea was a popular location if you were a pterosaurs. This one is 22% complete, which is a lot for pterosaur.

100-million-year-old fossil find reveals huge flying reptile that patrolled Australia’s inland sea

In 2021 a former avocado farmer discovered the most complete pterosaur skeleton ever found in Australia – and new research shows it represents a previously unknown species.

theconversation.com

My friend Peter is currently doing a reconstruction of one of our pterosaurs (forgotten which), the fossils tell an amazing story, the pterosaur has has been grabbed by an ichthyosaur. which in turn is bitten in half by a massive Kronosaur.

Is he naming them after himself or Joh Bjelke

 

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Another new horned dinosaur named Lokiceratops, I must confess I'm always partial to Norse god names. Lokiceratops was discovered in 2019 in the badlands of northern Montana. At 6.7 meters long and weighing 5 tons it was the largest of it's class. Nice reconstructions. The image I've used is from the article and shows 3 relatives.

The ornate horns of ancient marvel Lokiceratops point to evolutionary insights

What do you get when you cross Norse mythology with a 78-million-year-old ancestor to the Triceratops? Answer: Lokiceratops rangiformis, a plant-eating dinosaur with a very fancy set of horns.

phys.org

 

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An extinct 10-foot-long eagle could pick up kangaroos with its terrifying talons

Dynatoaetus gaffae boasts a 10 foot wingspan and went extinct with much of Australia’s other megafauna 50,000 years ago.

www.popsci.com

 

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This is a French doco on early mammals which looks at the amazing finds from Jurassic deposits in Liaoning, China. The is the same place the amazing dino fossils with skin and feather imprints come from. Not only are there almost complete fossils of our small ratty forebears there are a number of larger critters such as Repenomamus giganticus. Some nice reconstructions, though the animation of one of the feathered dinos looks poor. Covers the early evolution of mammals pretty well and highlights the major innovations. Small size, warm coats, adaptable reproductive strategies and a penchant for insects saw us out last dino's and survive the nuclear winter like conditions post comet strike,

 

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Size matters. Minds out of the gutter, it involves genome sizes. The South African lumgfish has the biggest vertebrate genome. One of it's chromosomes is equal in size to all ours put together. Because of its size it has long been speculation how this may have aided the development of those pesky feet that tetrapods needed 370 million years ago.

Largest animal genome sequenced — and just 1 chromosome is the size of the entire human genome

Scientists sequenced the largest known animal genome in a species of lungfish — ancient fish that breathe air.

www.livescience.com

 

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Peter is currently reconstruction Trilobites from Australian early Cambrian deposits, I can't post the pics until the paper is out. I can post some sources he is using, this video is based on CT scans of a large Moroccan trilobite that has been captured in amazing detail. I had to cut, and recompress the video quite a bit to get it small enough to upload.

View attachment Trilobite.mp4

 

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Three new thylacinids have been discovered, all smaller than the Tassy Tiger, the largest around 10 kg was Badjcinus timfaulkneri, seen below getting lunch, almost but not quite, wombat stew.

Scientists dissolved a boulder in acid – and a thylacine jumped out

The bone-crushing fossilised jaws were one of three Tasmanian tiger ancestors uncovered by palaeontologists, amid a contentious effort to resurrect the marsupial carnivore.

www.smh.com.au