Information

Are there any 6 limbed reptile fossils?

Are there any 6 limbed reptile fossils?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Were any 6 armed "tetrapod" fossils ever found? I've seen some lobe finned fish with two sets of shoulders in an evolutionary bio book… I'm curious because I'd like 4 limbed and 2 winged dragons to have existed :)


I think, you misidentified the unpaired anal fin of coelacanth as an extra pair of limbs.

I personally haven't ever heard of six-legged vertebrates, although the phenomenon of supernumerary legs is well known as an anomaly. Such anomalies can be easily induced in different vertebrates (including mice: Rutledge et al), if you treat their embrya with retinoid acid (which normally defines embryonic polarity) or fibroblast growth factor. In nature, different factors can lead to development of extra legs, and the most well-known and wide-spread cases are limb abnormalities in amphibians, induced by trematodes and pollution (including retinoid acid mimics?) (Blaustein & Johnson).

That said, I would not be surprised by a discovery of a fossil amphibian with extra limbs. But such a find then should be interpreted as an abnormality, if not proved otherwise. It's true that the fore and the hind limbs are serial homologues, but their number seems to have been fixed very early (in contrast to the number of the fingers).


Reptile With 'Bizarre' Front Limbs Tweaks Current Understanding of Evolution

— -- A new study on 212-million-year-old fossils from an extinct reptile with strange arms has shed new light on our understanding of evolution.

A team of scientists analyzed the fossils of a drepanosaurus, a prehistoric reptile that has been described as a "chameleon-anteater hybrid," and found that the bone structure, especially in the front limbs, were unlike any other animals from that time period.

“This animal stretches the bounds of what we think can evolve in the limbs of four-footed animals,” Adam Pritchard, the lead author on the paper and a postdoctoral researcher at Yale University, said in a statement.

Pritchard, Alan Turner of Stony Brook University, Randall Irmis of the University of Utah, Sterling Nesbitt of Virginia Polytechnic Institute and State University, and Nathan Smith of the Dinosaur Institute at the Natural History Museum of Los Angeles co-authored the report and published their findings on Thursday in the journal Current Biology.

The fossils indicated that the animal's two arm bones, the radius and ulna, are different sizes, unlike most tetrapods (a general term for four-limbed animals).

“Ecologically, Drepanosaurus seems to be a sort of chameleon-anteater hybrid, which is really bizarre for the time. It possesses a totally unique forelimb,” Pritchard added.

The team of scientists also wrote that these unusual front arms are significant because the "structural relationships between the bones of the forelimb have remained largely unchanged throughout the 375 million year history of Tetrapoda."

The drepanosaurus also has an unusually long claw on one of its fingers.

The presence of a claw is also unique, according to the paper, because it "demonstrates that specialized, modern ecological roles had developed during the Triassic Period, over 200 million years ago."

The drepanosaurus fossils were discovered in Ghost Ranch, New Mexico, according to the report.


Ancient reptile fossils claw for more attention

In this illustration set 212 million years ago in what is today New Mexico, a Drepanosaurus rips away tree bark with its massive claw and powerful arm. Credit: Painting by Victor Leshyk

Newly recovered fossils confirm that Drepanosaurus, a prehistoric cross between a chameleon and an anteater, was a small reptile with a fearsome finger. The second digit of its forelimb sported a massive claw.

Scientists analyzed 212-million-year-old Drepanosaurus arm fossils that were discovered at the Hayden Quarry in Ghost Ranch, New Mexico. The researchers describe their findings in a paper in the Sept. 29 edition of the journal Current Biology.

Drepanosaurus is neither a dinosaur nor a lizard. It is a one- to two-foot long reptile from an extinct group of animals called drepanosaurs, and shares a common ancestry with lizards, crocodiles, and dinosaurs. The only other known Drepanosaurus fossil was a badly crushed skeleton found in northern Italy more than 30 years ago.

"This animal stretches the bounds of what we think can evolve in the limbs of four-footed animals," said Adam Pritchard, a postdoctoral researcher at Yale and first author of the study. "Ecologically, Drepanosaurus seems to be a sort of chameleon-anteater hybrid, which is really bizarre for the time. It possesses a totally unique forelimb."

Four-limbed animals with a backbone are called tetrapods. In nearly all tetrapods, the forearm is made up of two, elongate and parallel bones—the radius and the ulna. These bones connect to a series of much shorter, wrist bones at the base of the hand.

Drepanosaurus, however, has radius and ulna bones that are not parallel. Instead, the ulna is a flat, crescent-shaped bone. Also, the two wrist bones that meet the end of the ulna are long rather than short. They are longer than the radius, in fact.

"The bone contacts suggest that the enlarged claw of Drepanosaurus could have been hooked into insect nests," Pritchard said. "The entire arm could then have been powerfully retracted to tear open the nest. This motion is very similar to the hook-and-pull digging of living anteaters, which also eat insects."

Drepanosaurus also had grasping feet and a claw-like structure at the tip of its tail. The finding suggests that tetrapods developed specialized, modern ecological roles more than 200 million years ago.

Pritchard is a postdoctoral fellow in the lab of Bhart-Anjan Bhullar in the Department of Geology and Geophysics at Yale. Co-authors of the study were Alan Turner of Stony Brook University, Randall Irmis of the University of Utah, Sterling Nesbitt of Virginia Polytechnic Institute and State University, and Nathan Smith of the Dinosaur Institute at the Natural History Museum of Los Angeles County.


Prehistoric last meal: marine reptile fossil has beast in stomach

Fresh evidence of the dog-eat-dog world of prehistoric oceans has been revealed by fossil hunters who have unearthed the remains of a giant marine reptile with another huge beast in its stomach.

Dug up in south-western China in 2010, the animals are thought to have lived in the Middle Triassic.

The team say the larger fossil, nearly 5 metres in length, is the remains of an ichthyosaur – marine reptiles with a long snout, similar in appearance to a dolphin – while the smaller fossil within it is the middle section of a species called Xinpusaurus xingyiensis, a type of marine reptile known as a thalattosaur that was usually about 4 metres long.

The international team of researchers say the ichthyosaur, Guizhouichthyosaurus, was not previously thought to have been a top predator – not least because its teeth lacked cutting edges and were thought best suited to grasping soft prey such as squid. But the findings suggest otherwise, revealing its last meal was a creature larger than an adult human.

This image shows the ichthyosaur’s teeth, with the broken white line indicating the approximate gum line of the upper jaw. Photograph: iScience

“It likely represents the oldest record of megafaunal predation by a marine reptile,” the team wrote in the journal iScience, adding the discovery also broke records for the longest prey of such creatures.

The findings could change the reputations of other creatures too: “There were many more Mesozoic marine reptiles with similar grasping teeth, so megafaunal predation was likely more widespread than presently conceived,” the team said.

While the team said it remained unclear whether the ichthyosaur sought out the thalattosaur, or if it simply scavenged the meal, they said the former was more likely.

“If a predator other than Guizhouichthyosaurus killed the thalattosaur in question, then it would be strange for the nutritious trunk and limbs to be left intact by the predator,” they said. Among further evidence, they noted decomposition of a dead creature would have been fast, the head and tail of the thalattosaur appear to have been torn off before eating, while the thalattosaur was likely ingested near the surface as it would have taken time to swallow.

Dr Nick Fraser, a palaeontologist at National Museums Scotland who was not involved with the work, said it could often be difficult to be sure one creature had been eaten by another, rather than two fossils simply lying on top of each other, but that did not appear to be the case for the new find.

“In this case I find it very convincing that the Xinpusaurus is indeed the Guizhouichthyosaurus’ last meal,” he said, adding the peg-like teeth of the larger reptile made it surprising it could grasp and swallow the thalattosaur.

“I agree with the authors that [Xinpusaurus] was likely captured live rather than scavenged, but maybe [the thalattosaur] was not a healthy individual,” he said.

“In any event, I think it is clear that it was a step too far for the ichthyosaur. As such this might represent a rather uncommon event in a day in the life of a Triassic marine reptile. But it does rather magically bring to life a cameo of animal interactions in the seas approximately 230m years ago.”


The Institute for Creation Research

Many creationists and evolutionists alike are familiar with the initial huge explosion of complex marine life buried in the Cambrian rock layers at the beginning of the fossiliferous strata, 1 but few people know about the explosion of land-based life in the Carboniferous and Early Permian. While evolutionists have engendered a great deal of speculation about amphibians somehow morphing into reptiles as a central part of the grand evolutionary story and the early colonization of land, the supporting fossil evidence for this conjecture is lacking. Instead, we see a massive explosion of diverse amphibia and reptile-like creatures alongside a huge diversity of plant life and arthropods representing lowland coastal ecosystems. 2-6

When we consider these fossils in the Carboniferous and Early Permian rock layers, we have a direct witness to the enormous destruction and burial of lowland coastal ecosystems during the first phase of global land inundation in the Genesis Flood. 7

Amphibian Evolution Missing

Modern ecology of amphibia and reptile-like creatures is diverse. Most types live on land, underground, in trees, or in freshwater aquatic environments such as streams, lakes, and rivers. They are categorized as ectotherms (cold-blooded) because their body temperature is heavily influenced by external sources such as sunlight or warm surfaces. Many amphibians will start their lives in water, but some types have specific mechanisms to bypass this. They generally have complex life cycles, undergoing metamorphosis from a larva with gills to an adult with lungs that breathe air. One of the most amazing features of some amphibians is the ability to use their skin with their lungs to breathe. In fact, there are even a few small terrestrial frogs and salamanders that have no lungs and breathe completely through their skin.

The three main groups or orders of living amphibians are Anura (frogs and toads), Urodela (salamanders), and Apoda (the serpentine caecilians). Among secular scientists, the origins and evolutionary relationships between the three main groups of amphibians are hotly debated. 6 About 90% of the approximately 8,000 known amphibia are frogs, including a tiny frog that is the smallest known vertebrate, having a length of only 0.30 inches. Frogs and salamanders have no evolutionary history and show up suddenly in Jurassic strata looking similar to their living counterparts. Caecilians are a group of limbless amphibians shaped like earthworms. They are one of the least familiar amphibians because they live hidden in the ground and in stream beds. Their evolutionary origins are a complete mystery, with one alleged legged variant showing up in the Jurassic.

As far as the big picture of biological evolution goes, the idea of an amphibian as a transitional form plays an important role. Based solely on the premise of evolution (rather than fossil evidence), it is believed that the earliest amphibians evolved in the Devonian system (the so-called Age of Fishes) from lobe-finned fish with lungs (e.g., lungfish) and bony-limbed fins to somehow leave a watery life and live on dry land. As I showed in several previous articles, this whole claimed fish-to-tetrapod transition is absent in the fossil record. 6,8 Nevertheless, it is taught that after arriving on land, these ancient hypothetical amphibians diversified and became the dominant land creatures during the Carboniferous and Permian periods but were later displaced by reptiles and other vertebrates. Then, as the story goes, over millions of years amphibians became smaller and decreased in their diversity.

The problem with this amphibian evolutionary story is that extinct amphibian-like creatures appear suddenly and already diversified in the Carboniferous layers, while the three major groups of living amphibians appear suddenly without prior ancestors in the Jurassic. In previous articles, I showed how the Devonian strata contained only diverse types of fish and fish-like creatures, and how complex terrestrial life emerged suddenly afterward with no window for evolution. 6,8,9

Temnospondyli and Reptiliomorphs

Temnospondyli are a diverse group of small to giant amphibian-like creatures whose fossils have been found in the Carboniferous, Permian, and in the layers above on every continent. Their systems enable them to fill a wide range of habitats, including fresh water, terrestrial, and possibly coastal marine environments. They are considered amphibian-like based on a range of fossils representing a complex amphibian lifestyle (larval stage, metamorphosis, and maturity). Their bodily traits indicated they were semi-aquatic, although some were thought to be almost fully terrestrial&mdashpossibly returning to water to breed. In fact, it&rsquos possible that some temnospondyls were not amphibians at all since they had scales, claws, and armor-like bony plates.

Reptiliomorphs (or Anthracosauria) are a group of reptile-like tetrapods that appear suddenly and unexpectantly in the fossil record alongside the Temnospondyli, leaving virtually no room for amphibian-to-reptile evolution to occur. For example, Westlothiana (nicknamed &ldquoLizzie&rdquo) was discovered in early Carboniferous rocks, and although it clearly looked like a terrestrial lizard, it was not considered a true lizard largely because it was out of place in the tetrapod evolution story. In addition, many other lizard-like reptile creatures have been found in Carboniferous rock layers, such as Gephyrostegus and Limnoscelis. The main evolutionary problem is that terrestrial amphibian-like and reptile-like creatures appear in the same strata with no room for evolution to take place from one to the other.

Arthropods Galore

In my previous article I mentioned the sudden appearance of land life in the early Carboniferous, which also included arthropods such as giant scorpions. 6 The appearance of monster arthropods throughout the Carboniferous included huge dragonflies (Meganeura) with two-foot wingspans and a type of millipede called Arthropleura that was up to six feet long. While most believe that Meganeura preyed upon smaller arthropods and freshwater creatures, Arthropleura was actually a plant eater. We know this because the remnants of a lowland coastal tree called a lycopod have been found in its gut and coprolites (fossil feces). The presence of extremely sophisticated creatures like a dragonfly early in the rock record of land creatures does little to help the evolutionary story. Adult dragonflies have a complex life cycle. Their larvae live underwater as a vicious predator and then eventually metamorphosize into an adult dragonfly, one of the most complexly engineered insects known.

Carboniferous Coals

Another interesting aspect of the Carboniferous and Early Permian rock layers is the sudden appearance of true ferns and seed plants representing coastal lowland forests. Some of these plants like the Lepidodendron grew as tall as 100 feet. Not only does this sudden appearance of diverse plant life without any evolutionary ancestors to indicate a transition from growing in water to living on land present a problem, but so does the nature of the extensive mass burial of this plant matter. This huge mass of ripped-up plant debris had to have been buried rapidly to form the massive coal seams that are observed in various parts of the world. In fact, this is where we get the name Carboniferous, which means &ldquocoal bearing.&rdquo

Even more interesting is that these Carboniferous coal layers are buried with marine sediments. Marine limestone layers are common right above and below many of these coal beds. This has completely perplexed evolutionists who have for decades erroneously claimed that coals form slowly over deep time in freshwater environments. The late paleontologist Jennifer Clack noted that these massive Carboniferous coal seams indicate an &ldquoextensive, large-scale event&rdquo and &ldquothe coal forest sediments are covered by marine deposits.&rdquo When trying to surmise the sort of ecosystem that they might have represented, she said, &ldquoThe lowlands and marshy regions can support such extensive plant growth.&rdquo 4

Putting It All Together with the Global Flood

How is it that we find entire coastal lowland ecosystems catastrophically buried and preserved as fossils and coal&mdasha fossil fuel&mdashalong with sediments of marine origin in these Carboniferous rock layers? The answer is simple. If one abandons the false paradigm of evolution, which has little to offer in explaining the trends and complexities found in the fossil record, one finds a loving Creator specializing His creatures for their environments. As noted in this article, immediately above the Devonian strata (which is full of fish and other marine life) comes the Carboniferous layer where land arthropods, lizard and amphibian-like creatures, and coastal forest plants all suddenly appear together. In the global Flood model, we can easily explain this as the progressive destruction caused by the tsunami-like global floodwaters. A sweep of massive waves violently inundated the major landmasses in their lowland coastal regions. Because these coastal low-lying areas had very tropical climates and likely contained a lot of marsh-like forest habitats, we see in these layers both plants and animals that were specially adapted to these conditions.

According to the global mapping of Flood layers known as megasequences, the deposition of the Late and Early Carboniferous (and Permian) corresponds to the end of the Kaskaskia Megasequence and the beginning of the Absaroka. These two megasequences were part of the continual advance of the floodwaters across higher and higher elevations described in Genesis 7. These rock layers perfectly represent the global destruction of lowland ecological systems and reinforce a creationist model of paleontology based on global Flood burial by ecological zonation.


A 95-million-year-old reptile's solution to the problem of tooth wear

A piece of a Priosphenodon lower jaw found in the field in Argentina. Credit: Aaron LeBlanc, Author provided

Eating plants is a challenging diet for many animals. To help extract the rich plant nutrients, modern mammals have specialized teeth for crushing up the hard plant parts to give the digestive system a head start. But modern plant-eating reptiles usually take a different route.

A study published in Current Biology examined the complex and unique teeth of a 95-million-year-old plant-eating reptile, Priosphenodon avelesi. Where most plant-eating reptiles have relatively simple teeth that they can replace when worn down, Priosphenodon could not replace any of their teeth. Looking inside the teeth of Priosphenodon revealed that these hardy reptiles had evolved some elegant solutions to the problem of tooth wear.

Priosphenodon lived during the earliest part of the Late Cretaceous in what is now northern Patagonia. Fossils of this close relative of the modern New Zealand Tuatara are found in great abundance at the famous La Buitrera Palaeontological Area, in Río Negro Province, Argentina. This fossil locality is also well known for its rear-limbed snakes, mammals and dinosaurs.

The rocks at La Buitrera preserve evidence of an ancient sand sea, called ergs after the great Erg deserts of modern North Africa. Such environments can be seasonally rich as climate changes and plant communities prosper, which can stop the movement of dune sands.

Priosphenodon is the most abundant and one of the few plant-eating reptiles at La Buitrera. Similar to modern ecosystems where plant eaters greatly outnumber carnivores, the abundance of Priosphenodon fossils is tenfold to that of the known meat-eaters.

Reconstruction of the skeleton Priosphenodon avelasi made by the paleoartist Jorge González, and exhibited at the Carlos Ameghino Provincial Museum. Credit: Museo Provincial Carlos Ameghino

By using computed tomography (CT) scans and thin sections of fragments of Priosphenodon jaws, we unraveled the secrets locked inside the teeth of this unique reptile.

Reptiles typically have simple-looking, cone-shaped teeth that are covered in very thin enamel, which is the hardest layer on a tooth. As their teeth wear down, they continuously make new teeth to replace their old ones.

Priosphenodon is an exception to this rule. Having inherited an inability to replace old teeth from its sphenodontian relatives, this Cretaceous-era reptile did something very different. Priosphenodon teeth are more like half-cones that stack together lengthwise. The teeth are even folded along their bases into complex shapes like those of some plant-eating mammals.

These teeth were excellent tools for grinding and shredding.

The key ingredient that made Priosphenodon a successful plant-shredder lies inside its enamel. Details of the fossilized enamel reveal that it was made of tiny threads of enamel crystals, called prisms. This type of enamel has never been seen before in a fossil reptile, but it does show up in the teeth of virtually all mammals and helps prolong the life of each tooth.

  • The upper (left) and lower teeth (right) of Priosphenodon. The images on the right were generated from CT scans. Credit: Aaron LeBlanc, Author provided
  • Under a microscope, Priosphenodon enamel is made of the same tiny enamel threads (prisms) as in mammal enamel. This makes it very different from the simpler enamel of a typical reptile. Credit: Aaron LeBlanc, Author provided

But if reptiles have the ability to make this stronger type of enamel, why don't we see it in other kinds of reptiles? The answer lies in Priosphenodon's evolutionary heritage, as well as its diet.

Many other species of modern and fossil reptiles cannot replace their teeth, but very few are also as well adapted for eating plants as Priosphenodon. Having such durable teeth while being restricted to eating the tough desert plants of the Patagonian erg allowed Priosphenodon to thrive in this demanding environment.

Priosphenodon challenges our views of reptiles as having simple teeth compared to mammals, showing that under the right conditions, even reptiles can evolve extremely complex teeth.


Fossil distribution

The earliest known reptiles, Hylonomus and Paleothyris, date from Late Carboniferous deposits of North America. These reptiles were small lizardlike animals that apparently lived in forested habitats. They are the Eureptilia (true reptiles), and their presence during this suggests that they were distinct from a more primitive group, the anapsids (or Parareptilia). The early reptiles were usually small animals and generally were not as abundant as some of the synapsids, such as the sailback pelycosaurs (Edaphosaurus, Dimetrodon, and others). Assorted parareptiles occurred throughout the Permian Period (299 million to 251 million years ago), but they largely disappeared from the fossil record by the beginning of what was to become known as the “Age of Reptiles,” the Mesozoic Era (251 million to 65.5 million years ago). Nonetheless, they reappeared during the Late Triassic Epoch (229 million to 200 million years ago) as the first turtles, the most primitive of which was Proganochelys. Turtles regularly appear in fossil records thereafter. Of the eureptiles, the captorhinids were present throughout most of the Permian. These broad-headed lizardlike reptiles appear to have been agile carnivores of moderate size. They disappeared, apparently leaving no descendants, in the Late Permian, or Lopingian, Epoch (260 million to 251 million years ago).

With the possible exception of turtles (which are often labeled anapsids), modern reptiles and most reptiles of the Mesozoic Era are diapsids. One of the most-recognizable groups of diapsids is the lepidosauromorphs. This lineage, which is ancestral to today’s tuatara and squamates (lizards and snakes), appeared first during the Late Permian. Assorted squamates or squamate relatives began appearing in the Jurassic Period (200 million to 146 million years ago). During the Middle Jurassic Epoch (174.1 million to 163.5 million years ago), the earliest snakes evolved.

One of the main diversifications occurred within the suborder Sauria. Some of the most-specialized saurians, the ichthyosaurs and sauropterygians, appear first in the Early Triassic (251 million to 246 million years ago), and representatives of both groups occurred in the seas until the middle of the Cretaceous. The ichthyosaurs are reptiles with fishlike bodies they were live-bearers because their body form prevented beaching to lay eggs. The sauropterygians included an assortment of marine creatures this group included the plesiosaurs as well as forms that resembled modern-day turtles and walruses. The plesiosaurs have no modern-day analogs.

The archosauromorphs, a group of diapsids that includes the dinosaurs as well as modern crocodiles and birds, did not appear in the fossil record until the middle of the Triassic Period. The leather-winged pterosaurs, or “winged lizards,” were also archosauromorphs they persisted throughout the remainder of the Mesozoic Era. Crocodylomorphs and dinosaurs were present in the Early Jurassic Epoch (200 million to 176 million years ago), and their descendants live today in the forms of the crocodiles and birds.


New Jurassic flying reptile reveals the oldest opposed thumb

Life reconstruction of K. antipollicatus. Credit: Chuang Zhao

A new 160-million-year-old arboreal pterosaur species, dubbed 'Monkeydactyl', has the oldest true opposed thumb—a novel structure previously not known in pterosaurs.

An international team of researchers from China, Brazil, UK, Denmark and Japan have described a new Jurassic pterosaur Kunpengopterus antipollicatus, which was discovered in the Tiaojishan Formation of Liaoning, China.

It is a small-bodied darwinopteran pterosaur, with an estimated wingspan of 85 cm. Most importantly, the specimen was preserved with an opposed pollex ("thumb") on both hands.

The species name 'antipollicatus' means 'opposite thumbed' in ancient Greek, in light of the opposed thumb of the new species. This is the first discovery of a pterosaur with an opposed thumb. It also represents the earliest record of a true opposed thumb in Earth's history. The researchers published their discovery today in the journal Current Biology.

A true opposed pollex is mostly present in mammals (e.g. primates) and some tree frogs, but extremely rare among extant reptiles except for chameleons. This discovery adds to the list that darwinopteran pterosaurs such as K. antipollicatus also evolved an opposed thumb.

The research team scanned the fossil of K. antipollicatus using micro-computed tomography (micro-CT), a technique making use of X-ray to image an object. By studying its forelimb morphology and musculature, they suggest that K. antipollicatus could have used its hand for grasping, which is likely an adaptation for arboreal life.

In order to test the arboreal interpretation, the team analyzed K. antipollicatus and other pterosaurs using a set of anatomical characters related to arboreal adaptation. The results support K. antipollicatus as an arboreal species, but not the other pterosaurs from the same ecosystem. This suggests niche-partitioning among these pterosaurs and provides the first quantitative evidence that at least some darwinopteran pterosaurs were arboreal.

Fion Waisum Ma, co-author of the study and Ph.D. researcher at the University of Birmingham, said: "The fingers of 'Monkeydactyl' are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through the rocks, create digital models and tell how the opposed thumb articulates with the other finger bones.

"This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur—which wasn't known for having an opposed thumb."

Xuanyu Zhou from China University of Geosciences who led the study commented: "Tiaojishan palaeoforest is home to many organisms, including three genera of darwinopteran pterosaurs. Our results show that K. antipollicatus has occupied a different niche from Darwinopterus and Wukongopterus, which has likely minimized competition among these pterosaurs."

Rodrigo V. Pêgas from Federal University of ABC, in Sao Bernardo, Brazil, said: "Darwinopterans are a group of pterosaurs from the Jurassic of China and Europe, named after Darwin due to their unique transitional anatomy that has revealed how evolution affected the anatomy of pterosaurs throughout time.

"On top of that, a particular darwinopteran fossil has been preserved with two associated eggs, revealing clues to pterosaur reproduction. They've always been considered precious fossils for these reasons and it is impressive that new darwinopteran species continue to surprise us!"


Biologists say recently discovered fossil shows transition of a reptile from life on land to life in the sea

Vadasaurus herzogi fossil. Credit: Mick EllisonUsed with permission from the American Museum of Natural History

Using modern research tools on a 155-million-year-old reptile fossil, scientists at Johns Hopkins and the American Museum of Natural History report they have filled in some important clues to the evolution of animals that once roamed land and transitioned to life in the water.

A report on the new discoveries about the reptile, Vadasaurus herzogi, appears online in the Nov. 8 issue of Royal Society Open Science, and suggests that some of the foot-long animal's features, including its elongated, whip-like tail, and triangular-shaped head, are well suited to aquatic life, while its relatively large limbs link it to land-loving species.

Vadasaurus, which is the Latin term for "wading lizard," was discovered in limestone quarries near Solnhofen, Germany, part of a once-shallow sea long explored for its rich trove of fossil finds.

The well-preserved fossil is housed in the American Museum of Natural History in New York, where the job of unlocking its evolutionary secrets fell to museum research associate Gabriel Bever, Ph.D., who is also assistant professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine, and Mark Norell, Ph.D., the museum's paleontology division chair.

"Anatomic and behavioral characteristics of modern groups of living things accumulated over long spans of time," says Bever. "Fossils can teach us a lot about that evolutionary history, including the order in which those features evolved and their adaptive role in a changing environment."

"Anytime we can get a fossil like this that is so well preserved, and so significant in understanding a major environmental transition, it is very important," says Norell. "It's so important," he adds, "that we can consider Vadasaurus to be the Archaeopteryx of rynchocephalians."

According to Bever, their work adds to the list of sea creatures whose ancestors were land-dwelling vertebrates. They include modern-day whales, seals, and sea snakes, and ancient (and now-extinct) species of ichthyosaurs, mosasaur, and plesiosaurs.

Bever says their study offers evidence that Vadasaurus, likely an adult when it died, can be linked by its anatomy to a small group of marine species called pleurosaurs, which have long been thought to have terrestrial roots. Pleurosaurs lived during the Jurassic period, 185 to 150 million years ago. The eel-like creatures had reduced limbs that were probably used for steering rather than propulsion in the water. Until now, fossils of only three ancient species of pleurosaurs have been discovered.

Using two types of statistical algorithms and reconstructions of evolutionary "trees," Bever and Norell say that Vadasaurus and the pleurosaurs are part of a larger lineage of reptiles called Rhynchocephalia. Like the sea-loving pleurosaurs, Vadasaurus' skull was a triangular shape, an adaptation found among many streamlined, water-dwelling animals, such as most fish, eels and whales. An elongated snout, common among sea animals, featured teeth farther away from the body for ensnaring fish.

By examining the shape and structure of the Vadasaurus' skull, Bever and Norell also concluded that Vadasaurus' bite was likely a quick, side-to-side motion, compared with the slower, stronger bite typical of many land-dwelling animals.

Some 155 million years ago, Vadasaurus' tail had begun to lengthen like most modern sea animals, says Bever, but not to the size of the 5-foot pleurosaur. Vadasaurus, they found, had 24 pre-sacral vertebrae, which span from the head to the beginning of the tail, whereas pleurosaurus had more than 50 such back bones.

Despite its aquatic features, Vadasaurus retained some features more often found among land vertebrates. For example, Vadasaurus still had the large limbs, relative to the size of its body, expected of a land-dwelling reptile. Bever speculates that Vadasaurus did not use its limbs for propulsion in the water, but to steer. He says Vadasaurus may have swum like a modern sea snake, moving its spinal column with an undulating kind of motion.

"Our data indicate that Vadasaurus is an early cousin of the pleurosaur," says Bever. "And these two reptiles are closely related to modern tuatara." The modern tuatara is a lizard-like, land-dwelling reptile that lives on New Zealand's coastal islands and is the single remaining species of rhynchocephalian still left on Earth.

Bever notes that a complete evolutionary history of Vadasaurus will require more data and fossil finds.

"We don't know exactly how much time Vadasaurus was spending on land versus in the water. It may be that the animal developed its aquatic adaptations for some other reason, and that these changes just happened to be advantageous for life in the water," says Bever.


The Institute for Creation Research

Permian rock layers contain several of the fossil record&rsquos greatest evolutionary enigmas. These rocks are found directly above Carboniferous strata, which I explained in the previous two articles in this series. 1-2 One enigma is the famous and hotly debated Permian-Triassic (P-T) mass extinction that included a dramatic shift in plant fossils, along with huge disappearances of marine life in the fossil record and, to a lesser degree, terrestrial creatures.

The other enigma is the sudden appearance of a whole host of extinct strange creatures that defy evolutionary explanation, along with others that are still alive today. However, these mysteries dissolve away when we place these plants and animals within a global Flood model of burial by ecological zonation.

Permian Rocks Are Flood-Formed

Land life buried in Permian sedimentary rock units include diverse plants, arthropods, and a huge diversity of highly specialized and unique reptile-like creatures that are no longer living today. Evolutionists have claimed that many of these creatures lived in a massive arid desert environment simply based on the fact that they were buried in sandstone, commonly a type of water-deposited sedimentary rock.

In fact, secular scientists have claimed that these deposits represent ancient wind-blown sand dunes despite the fact that it&rsquos quite obvious they contain features that could only have formed by water. In recent years, extensive research has been completed on these rock units by analyzing sedimentary structures (cross-bedding) and microscopic thin sections, looking at sediment particles within the rocks and comparing these data to present-day sand dunes. 3 The clear implication of these data is that Permian deposits were unequivocally formed in a massive catastrophic flood.

Plants and Living Fossils

Much of the plant life found buried in Permian strata overlaps with the Late Carboniferous (Pennsylvanian system) strata, such as the swamp-like large plants that grew as tall as 100 feet called Lepidodendron and Sigillaria. 4-6 However, seed ferns and conifers also began to be buried in these Flood sediments since they would have been living slightly more inland from the coastal forests and swamp-like ocean shorelines representing the land fossils in the Carboniferous layers.

The various conifer plant groups were a diverse mix, and these ecosystems also included large trees like ginkgoes and cycads along with seed ferns. Not only are many types of cycads still with us today in rainforests near coastal regions but also ginkgoes, which not only appeared suddenly in the fossil record but look exactly like ginkgo trees growing around the world today. Thus, the beautiful ginkgo tree enjoyed by many gardeners and horticulturists is considered a living fossil that defies evolution. In addition, conifers found in Permian strata are very similar in appearance to current living counterparts and were as broadly adapted to diverse ecosystems as many conifers are today.

Insect Fossils Galore

Beginning in the Late Carboniferous layers and continuing through the Permian are many different types of insects such as dragonflies, numerous types of beetles (Coleoptera), true bugs (Hemiptera), and even grasshopper/cricket-like insects (Orthoptera). 4-6 In fact, all of these major groups of insects (known as orders) appear suddenly in the fossil record without any evolutionary precursors and look similar to counterparts living among us today. But even more interesting is the fact that the Permian rocks contain a huge diversity and abundance of cockroach-like insects.

When we consider these types of fossils, it&rsquos important to keep in mind that insects are extremely sophisticated creatures with a diversity of folding wing and flight systems, complex compound eyes, sophisticated antennas with amazing sensor systems, versatile digestive systems, spectacularly complex and efficient mouthparts, and rugged and versatile chitin-based exoskeletons. Not only do all of these land arthropod creatures appear suddenly and fully formed in these rock layers, but their traits would have made them ideally suited to life in the near-coastal tropical rainforest ecosystems represented by other Permian fossils.

Reptile Fossils

Reptile and reptile-like fossils tend to get the most attention when secular scientists discuss the Permian rocks because of their sudden appearance and spectacular traits. 4-6 In fact, there are so many different types of reptile creatures whose fossils are found in these rock layers that it&rsquos only possible to highlight a few of the most interesting.

One prominent group of creatures commonly found in Early Permian layers are the pelycosaurs, which included reptiles with spectacular sail-like structures on their backs that integrated with their spinal vertebrae and were thought to provide some sort of thermoregulatory function (edaphosaurids and sphenacodontids). Some of the more well-known members of these groups are Edaphosaurus, Dimetrodon, and Gordodon. Other diverse groups of reptiles without these unusual sails also existed, such as the diadectids.

Another amazing group of reptiles found in Permian layers had wing-like structures that allowed them to glide through the air&mdashperhaps jumping out of trees as the Draco flying (gliding) lizard does, which is alive today and commonly observed in the forests of South Asia. One striking example of a flying lizard from Permian rocks is Coelurosauravus, which had a gliding mechanism unlike that of any other known tetrapod. The lateral gliding membrane featured bony rods independent of the ribcage and arranged to form a wing-like structure. And of course, none of these animals have any identified ancestors in rock layers below the Permian level.

Mammal-Like Reptiles?

Also appearing in the Permian rocks are what evolutionists have claimed were the first cynodonts. These were reptile-like creatures called therapsids that secular scientists imagine somehow evolved into the first mammals later in the Triassic, such as the oft-cited example of Moschops. While evolutionists originally widely used the term mammal-like reptiles, this phrase caused much consternation among paleontologists and those trying to sort out taxonomic groupings over the years.

Now they are referred to by secular scientists as stem mammals or proto-mammals, but these terms are also tainted with evolutionary fiction. The fact of the matter is that while these animals had some unusual teeth, skull structures, and more vertically placed legs than typical lizards, they were clearly reptile-like creatures. Despite the claims of evolutionists, there&rsquos little evidence for this unique group of reptiles to support an evolutionary story of a transition from a reptile to a mammal.

Permian-Triassic Extinction Event

According to the evolutionary story, the end of the Permian was marked by the most extensive extinction event in the rock record, termed the P-T extinction. 4-6 It&rsquos claimed that approximately 90% of marine species went extinct, along with about 70% of all land species, including a mass extinction of insects. Trilobites, common marine arthropod creatures found in earlier strata down into the Cambrian, went fully extinct about this time. And other marine creatures found in the Permian&mdashlike nautiloids, brachiopods, and bryozoans (sedentary filter-feeding animals), clams and gastropods, and other ocean creatures&mdashnearly disappeared, albeit a few species survived to the present with much less diversity than existed in the pre-Flood oceans.

One of the main problems evolutionists have in interpreting the P-T extinction event is that the timing of its specific details is very convoluted and drawn out (in evolutionary deep-time thinking). Many now-extinct Permian marine creatures were abundant right up to the close of the Permian deposition but, as mentioned above, land life was less represented in the extinction&mdashespecially land plants, which supposedly had a more extended extinction carrying on into the Triassic layers above. In other words, why the more sudden and more extensive marine extinction compared to the more spread-out land extinction? And why is the timing different between land animals, land plants, and marine creatures regarding the extinction?

Another problem secular scientists have with the P-T extinction is the progressive nature of the event based on conflicting and variable fossils assigned to various Permian deposits around the world. In fact, a number of scientists have claimed there were multiple extinctions over millions of years throughout the Permian leading up to the big one at the end.

Needless to say, this evolutionarily convoluted and extended so-called mass extinction is very difficult to explain when you want to add millions of years to the mix. Alleged mechanisms for it have varied between diverse hypotheses incorporating multiple meteor strikes, volcanic activity, ocean chemistry changes, global cooling, and even intense radiation from a nearby supernova. In fact, at this point many evolutionists now argue that the big P-T extinction was caused by a combination of some or all of the hypotheses listed above.

Explaining the Permian Perplexities with the Global Flood

One of the main mechanisms for the global Flood involved the progressive creation of hot and buoyant seafloor. 7 This pushed the ocean level up higher and higher, causing the progressive inundation of land by ocean water and marine sediments. Permian deposits are rich in marine creatures that would have been found in shallow, tropical seas. For example, fossilized shells of two kinds of invertebrates are widely used to identify and correlate Permian strata: fusulinids, a kind of shelled amoeba-like protist (a foraminiferan) and ammonoids (cephalopods with shells) that share features with the living chambered nautilus today. These diagnostic creatures, along with others entombed with them, indicate and validate the progressive and global nature of the Genesis Flood. Thus, Permian strata represent the increasing perturbation of the offshore ocean ecosystems along with the progressive burying of higher-elevation land environments just above the coastal forests and swamps represented in the Carboniferous strata.

In the global Flood model of progressively laying down global megasequences, the Permian level falls within the early Absaroka Megasequence. 7 This makes perfect sense since the Absaroka also begins with the Late Carboniferous sediments, which have extensive overlap with the Early Permian in regard to the types of plants and animals that are entombed within it. Thus, we can clearly see the progressive burial of land-based ecosystems starting at the interior edge of the lycopod coastal forests and swamps found in Carboniferous strata and extending into the higher-elevation, near-coastal tropical rainforests found in Permian strata. As we look higher in the Permian strata, we see fossils representing progressively higher elevations and leading into layers where the Permian terminates the Paleozoic.

According to this Genesis Flood model, the pre-Flood mega-continent of Pangaea would still have been largely intact at this stage&mdasha global geological configuration that even the secular world affirms for the Permian. However, because evolutionists fail to acknowledge the authenticity of the Genesis Flood account, their model makes little sense and, as we have seen, is full of discrepancies.

When we integrate paleontology with the geology of the global Flood, the data fit together quite nicely. There was no real extinction marking the P-T, only last appearances of many types of flora and fauna due to the progressive nature of the Flood as it inundated different ecosystems.


Watch the video: 10 ΕΦΕΥΡΕΣΕΙΣ της NASA που χρησιμοποιούμε καθημερινά - Τα Καλύτερα Top10 (February 2023).