Prehistoric amphibians, four or five fingers?


This 2016 video says about itself:

OSTEOHISTOLOGICAL AND COMPUTED FEA OF METOPOSAURUS KRASIEJOWENSIS SKULL BIOMECHANICS

By Kamil Gruntmejer

Recorded at XIV Annual Meeting of the European Association of Vertebrate Palaeontologists, Teylers Museum, Haarlem, Netherlands.

From the University of Bonn in Germany:

Fossil tracks: Wrong number of fingers leads down wrong track

July 24, 2020

Have you ever wondered why our hands have five fingers? And what about amphibians? They usually only have four. Until now it was assumed that this was already the case with the early ancestors of today’s frogs and salamanders, the Temnospondyli. However, a new find of the crocodile-like Temnospondyl Metoposaurus krasiejowensis from the late Triassic (about 225 million years old) in Poland shows five metacarpal bones and thus five fingers. As the researchers from the Universities of Bonn and Opole (Poland) note, this finding is very important, because until now, fossil animal tracks may have been wrongly assigned. The results have now been published in the Journal of Anatomy.

Modern amphibians usually have four fingers on the forelimb (and never more), which is called a “four-rayed hand,” as opposed to our five-rayed hand. Of all groups of terrestrial vertebrates, amphibians show the greatest variation in the number of frontfingers. Reptiles are the most conservative and usually have five. In birds, the finger bones in the wing have been lost completely. In mammals, the number of toes in the forelimb also varies greatly: Primates and raccoons have five, in horses only the third has survived, while in cattle and other even-toed ungulates fingers three and four remain. What they all have in common, however, is that this loss of toes or fingers originates from a five-ray pattern, which is why amphibians cannot be the ancestors of all these terrestrial vertebrate groups.

Exact number of toes is controversial

It has been known for some time that the earliest quadrupeds had significantly more fingers than five, such as Acanthostega, which had eight in the forelimb, or Ichthyostega with seven in the hind foot. As early as 300 million years ago, all but the five-fingered forms became extinct. The five-ray pattern was then retained in the real land animals, but was reduced again and again (see horses). The ancestors of today’s amphibians, the Temnospondyli, presented contradictory evidence of skeletons with four fingers, but also tracks that had five.

Temnospondyli is an important group of the early, very diverse quadrupeds. Some temnospondyls became as big as crocodiles, others were rather small. However, like all amphibians, they were dependent on water during their larval stage. Their most famous representatives include Eryops or Mastodonsaurus. “It’s also important to understand the evolution of modern amphibians, as this group probably evolved from the Temnospondyli,” says Dr. Dorota Konietzko-Meier from the Institute for Geosciences at the University of Bonn, who discovered and prepared the left forelimb of a Metoposaurus krasiejowensis in Krasiejów (southwest Poland).

However, despite the long history of research, the exact number of fingers in Metoposaurus and other temnospondyls is still controversial. “It’s remarkable that even in the case of the very well-researched Eryops, the skeletal reconstruction exhibited at the Muséum National d’Histoire Naturelle in Paris has five fingers, while only four fingers can be seen at the National Museum of Natural History in Washington,” says Ella Teschner, a doctoral student from Bonn and Opole. Lately, science has assumed that, similar to most modern amphibians, all Temnospondyli have only four toes in their forelimbs. This resulted in the five-toed footprints common in the Permian and Triassic periods being almost automatically assumed to not belong to Temnospondyli.

“The find from the famous Upper Triassic site Krasiejów in Poland therefore offers a new opportunity to study the architecture and development of the hand of the early quadrupeds,” says paleontologist Prof. Dr. Martin Sander from the University of Bonn. A considerably broader view of the entire group of Temnospondyli did not show a clear trend with regard to the five-ray pattern and suggested that the number of digits was not as limited in the phylogenetic context as was assumed. “Evidently, the temnospondyls were already experimenting with the four-ray pattern, and the five-ray pattern died out before the emergence of modern amphibians,” adds Sander.

Five fingers on each hand?

“Even if the ossification of five metacarpal bones described here was only a pathology, it still shows that a five-ray pattern was possible in Temnospondyli,” says Konietzko-Meier. However, it could not be assumed with certainty that the reduction in the number of fingers/digits from five to four always affected the fifth place on the hand in these fossil taxa. The possibility that some of the four-fingered taxa were caused by the loss of the first ray cannot be excluded. Sander: “The new finding of a five-fingered hand is particularly important for the interpretation of tracks, as it shows that a five-fingered forefoot print could also belong to the Temnospondyli and thus indicate a considerably wider distribution area of these animals.”

These results are also of general importance, since limb development plays an important role in evolutionary biology and medicine, and fossils may therefore provide important information for the evaluation of theories of hand development.

Beelzebufo, big dinosaur age Madagascar frog


This 22 July 2020 video says about itself:

Untangling the origins of Beelzebufo — the giant frog that lived alongside the dinosaurs — turns out to be one of the most bedeviling problems in the history of amphibians.

Triassic era catastrophes and wildlife


This 18 June 2020 video from the USA says about itself:

Big Amphibians of the Chinle Formation!

Dinosaur Journey Re-Opens today! And to celebrate we wanted to share a video of Dr. Julia McHugh talking amphibians. Ever noticed the large red rock base of Independence Monument?! Well, that’s the Triassic age rock these amazing creatures were discovered. WATCH now to learn more!

From the University of Texas at Austin in the USA:

Arizona rock core sheds light on Triassic dark ages

July 20, 2020

A rock core from Petrified Forest National Park, Arizona, has given scientists a powerful new tool to understand how catastrophic events shaped Earth’s ecosystems before the rise of the dinosaurs.

The quarter-mile core is from an important part of the Triassic Period when life on Earth endured a series of cataclysmic events: Our planet was struck at least three times by mountain-sized asteroids, chains of volcanoes erupted to choke the sky with greenhouse gases, and tectonic movement tore apart Earth’s single supercontinent, Pangea.

Among the chaos, many plants and animals, including some of the long-snouted and armored reptiles that ruled Pangea throughout the Triassic, vanished in a possible shake-up of life on Earth that scientists have yet to explain.

The study, published July 20 in GSA Bulletin, offers scientists a foundation to explain the changes in the fossil record and determine how these events may have shaped life on Earth.

By determining the age of the rock core, researchers were able to piece together a continuous, unbroken stretch of Earth’s history from 225 million to 209 million years ago. The timeline offers insight into what has been a geologic dark age and will help scientists investigate abrupt environmental changes from the peak of the Late Triassic and how they affected the plants and animals of the time.

“The core lets us wind the clock back 225 million years when Petrified Forest National Park was a tropical hothouse populated by crocodile-like reptiles and turkey-size early dinosaurs,” said Cornelia Rasmussen, a postdoctoral researcher at the University of Texas Institute for Geophysics (UTIG), who led the analysis that determined the age of the core.

“We can now begin to interpret changes in the fossil record, such as whether changes in the plant and animal world at the time were caused by an asteroid impact or rather by slow geographic changes of the supercontinent drifting apart,” she said.

Petrified Forest National Park’s paleontologist Adam Marsh said that despite a rich collection of fossils from the period in North America, until now there was little information on the Late Triassic’s timeline because most of what scientists knew came from studying outcrops of exposed rock pushed to the surface by tectonic movements.

“Outcrops are like broken pieces of a puzzle,” said Marsh, who earned his Ph.D. from The University of Texas at Austin’s Jackson School of Geosciences. “It is incredibly difficult to piece together a continuous timeline from their exposed and weathered faces.”

Marsh was not an author of the study but is part of the larger scientific coring project. UTIG is a unit of the Jackson School.

The Petrified Forest National Park core overcomes the broken puzzle problem by recovering every layer in the order it was deposited. Like tree rings, scientists can then match those layers with the fossil and climate record.

To find the age of each layer, the researchers searched the rock core for tiny crystals of the mineral zircon, which are spewed into the sky during volcanic eruptions. Zircons are a date stamp for the sediments with which they are buried. Researchers then compared the age of the crystals with traces of ancient magnetism stored in the rocks to help develop a precise geologic timeline.

Geoscience is rarely so simple, however, and according to Rasmussen, the analysis of the core gave them two slightly different stories. One shows evidence that a shake-up in the species might not be connected to any single catastrophic event and could simply be part of the ordinary course of gradual evolution. The other shows a possible correlation between the change in the fossil record and a powerful asteroid impact, which left behind a crater in Canada over 62 miles wide.

For Marsh, the different findings are just part of the process to reach the truth.

“The two age models are not problematic and will help guide future studies,” he said.

The research is the latest outcome of the Colorado Plateau Coring Project. The research and the coring project were funded by the National Science Foundation and International Continental Drilling Program.

Crested newts DNA research


This 30 June 2020 video from the Netherlands says about itself:

Some newts have a genetic malfunction that causes half of the eggs to cease. How is that possible? Manon de Visser is investigating this at Naturalis and the University of Leiden (Wielstra lab) and tells you everything about it in her first DNA talk!

Caecilian amphibians’ snake-like venom, new discovery


This 2017 video says about itself:

On this episode of Breaking Trail, Coyote discovers the most bizarre creature he’s ever found, a Caecilian!

Wait a what?! A Caecilian, while at first glance looks exactly like a giant earthworm, is actually an amphibian more closely related to salamanders. It’s definitely NOT a worm.

These subterranean crawlies live in the loose soils and substrates all over the world. They are very elusive and almost never seen by humans, so even though the rain forced the camera crew to take shelter Coyote just had to share this amazing encounter with the Coyote Pack!

Get ready to see one of the rarest creatures we will ever show you!

From ScienceDaily:

First evidence of snake-like venom glands found in amphibians

July 3, 2020

Caecilians are limbless amphibians that, to the untrained eye, can be easily mistaken for snakes. Though caecilians are only distantly related to their reptilian cousins, researchers in a study appearing July 3 in the journal iScience describe specialized glands found along the teeth of the ringed caecilian (Siphonops annulatus), which have the same biological origin and possibly similar function to the venom glands of snakes. If further research can confirm that the glands contain venom, caecilians may represent the oldest land-dwelling vertebrate animal with oral venom glands.

Caecilians are peculiar creatures, being nearly blind and using a combination of facial tentacles and slime to navigate their underground tunnels. “These animals produce two types of secretions — one is found mostly in the tail that is poisonous, while the head produces a mucus to help with crawling through the earth,” says senior author Carlos Jared, a biologist and Director of the Structural Biology Lab at the Butantan Institute in São Paulo. “Because caecilians are one of the least-studied vertebrates, their biology is a black box full of surprises.”

“It is while examining the mucous glands of the ringed caecilian that I stumbled upon a never before described set of glands closer to the teeth,” says first author Pedro Luiz Mailho-Fontana, a post-doctoral student in the Structural Biology Lab at the Butantan Institute.

What Mailho-Fontana found were a series of small fluid-filled glands in the upper and lower jaw, with long ducts that opened at the base of each tooth. Using embryonic analysis, he found that these oral glands originated from a different tissue than the slime and poison glands found in the caecilian’s skin. “The poisonous skin glands of the ringed caecilian form from the epidermis, but these oral glands develop from the dental tissue, and this is the same developmental origin we find in the venom glands of reptiles,” says Mailho-Fontana. This marks the first time glands of this kind have been found in an amphibian.

Researchers suspect that the ringed caecilian may use the secretions from these snake-like oral glands to incapacitate its prey. “Since caecilians have no arms or legs, the mouth is the only tool they have to hunt,” says co-author Marta Maria Antoniazzi, an evolutionary biologist at the Butantan Institute. “We believe they activate their oral glands the moment they bite down, and specialized biomolecules are incorporated into their secretions.

A preliminary chemical analysis of the oral gland secretions of the ringed caecilian found high activity of phospholipase A2, a common protein found in the toxins of venomous animals. “The phospholipase A2 protein is uncommon in non-venomous species, but we do find it in the venom of bees, wasps, and many kinds of reptiles,” says Mailho-Fontana. In fact, the biological activity of phospholipase A2 found in the ringed caecilian was higher than what is found in some rattlesnakes. Still, more biochemical analysis is needed to confirm whether the glandular secretions are toxic.

If future work can verify the secretions are toxic, caecilian oral glands could indicate an early evolutionary design of oral venom organs. “Unlike snakes which have few glands with a large bank of venom, the ringed caecilian has many small glands with minor amounts of fluid. Perhaps caecilians represent a more primitive form of venom gland evolution. Snakes appeared in the Cretaceous probably 100 million years ago, but caecilians are far older, being roughly 250 million years old,” Jared says.

Very few groups of land-dwelling vertebrates have serpent-like bodies, and this research suggests there might be a connection between a limbless body plan and the evolution of a venomous bite. “For snakes and caecilians, the head is the sole unit to explore the environment, to fight, to eat, and to kill,” says Antoniazzi. “One theory is that perhaps these necessities encourage the evolution of venom in limbless animals.”

How fish evolve into terrestrial animals


This 2018 video says about itself:

Fashionable Leaping Blennies | Planet Earth: Blue Planet II

Looking for love isn’t easy when you’re a blenny, but with a bright orange fin and a little determination, anything’s possible.

From the British Ecological Society:

How fish got onto land, and stayed there

June 17, 2020

Research on blennies, a family of fish that have repeatedly left the sea for land, suggests that being a ‘jack of all trades’ allows species to make the dramatic transition onto land but adapting into a ‘master of one’ allows them to stay there. The findings are published in the British Ecological Society journal Functional Ecology.

Researchers from the University of New South Wales and the University of Minnesota pooled data on hundreds of species of blennies, a diverse family of fish where some are aquatic and others have left the water completely. They found that a flexible diet and behaviour were likely to be instrumental in the transition to land.

However, once out of the water, restrictions on the type of food available triggered major evolutionary changes, particularly to their teeth, as land-dwelling blennies have become specialists in scraping algae and detritus from rocks.

Dr Terry Ord, lead author of the research, said: “The implications of our findings are that having a broad diet or being behaviourally flexible can help you move into a new habitat. But once there, this flexibility becomes eroded by natural selection. This presumably means those highly specialised species are less likely to be able to make further transitions, or cope with abrupt environment changes in their existing habitat.”

The scenario of fish colonising land has obvious parallels with the origin of all land vertebrates. “Fossils can give us important insights into how that transition might have unfolded, and the types of evolutionary adaptations it required or produced. But having a contemporary example of fish making similar ecological transitions can also help us understand the general challenges that are faced by fish out of the water” said Dr Ord.

Blennies are a remarkable family of fish with different species occupying strikingly different environments. Some are aquatic. Others spend time in and out of the water in the intertidal zone, an extreme environment with fluctuating water levels and pools that can rapidly change in temperature and oxygen levels.

Some species of blenny are terrestrial and spend almost their entire lives out of the water in the splash zone and must keep moist in order to breathe through their skin and gills. Despite these challenges, blennies have been incredibly successful in repeatedly making these dramatic transitions.

Because of this diversity, different blenny fish species represent clearly defined stages of the invasion process between two completely different environments. This makes them a unique group of animals to study.

Dr Ord explained the origin of the study with his co-author Dr Peter Hundt: “We both had extensive data collected on many different species of blenny from across the world. Peter had detailed information on diet and teeth morphology, while I had lots of data on behaviour and frequency of different species emerging from water for brief or extended periods on land.

“We threw a set of complex evolutionary statistical models at this combined data and we were able to reveal the sequence of events that likely allowed aquatic marine fishes to ultimately evolve into fishes that could leave water and then colonise land. Our study also showed how those species on land adaptively changed to better suit the specialised diet needed to survive on land.”

The authors caution that although the observational data suggests a flexible diet and behaviour allows a transition to new environments to occur, it cannot confirm causality. “Ideally we would perform some type of experimental investigation to try to establish casualty. What this experimental study might be is hard to imagine at this stage, but we’re working on it.” Said Dr Ord.

The authors are also looking to further investigate how the invasion of land has impacted other aspects of blenny fish behaviour, ecology and bodies. “Terrestrial blennies are really agile out of water, and I suspect they’ve adapted their body shape to allow them to hop about the rocks so freely. Which in turn implies they might not be able to go back to the water” said Dr Ord, “It would also be exciting to know how their sensory systems might have adapted out of the water as well, given vision and smell would probably work quite differently in these environments.”

New diamond frog species discovery in Madagascar


Rhombophryne ellae. Image credit: Mark Scherz

From ScienceDaily:

Shining like a diamond: A new species of diamond frog from northern Madagascar

June 16, 2020

Despite the active ongoing taxonomic progress on Madagascar’s frogs, the amphibian inventory of this hyper-diverse island is still very far from being complete. The known diversity of the diamond frog genus Rhombophryne in Madagascar has increased significantly (more than doubled!) over the last 10 years, but still there are several undescribed candidate species awaiting description. New species are constantly being discovered in Madagascar, often even within already well-studied areas. One such place is the Montagne d’Ambre National Park in northern Madagascar.

Montagne d’Ambre National Park is widely known for its endemic flora and fauna, waterfalls and crater lakes, and considered to be a relatively well-studied area. Yet, only two studies have been published so far on the reptiles and amphibians of the Park.

Serving the pursuit of knowledge of the herpetofauna in the region, Germany-based herpetologist Dr. Mark D. Scherz (Bavarian State Collection of Zoology, Technical University of Braunschweig, University of Konstanz) published a description of a new diamond frog species: Rhombophryne ellae, in the open-access journal Zoosystematics and Evolution.

“As soon as I saw this frog, I knew it was a new species,” shares Dr. Scherz, “The orange flash-markings on the legs and the large black spots on the hip made it immediately obvious to me. During my Master’s and PhD research, I studied this genus and described several species, and there are no described species with such orange legs, and only few species have these black markings on the hip. It’s rare that we find a frog and are immediately able to recognise that it is a new species without having to wait for the DNA sequence results to come back, so this was elating.”

The new species is most closely related to a poorly-known and still undescribed species from Tsaratanana in northern Madagascar, but is otherwise quite different from all other diamond frogs. With the orange colouration on its legs, Rhombophryne ellae joins the growing list of frogs that have red to orange flash-markings. The function of this striking colouration remains unknown, despite having evolved repeatedly in frogs, including numerous times in Madagascar’s narrow-mouthed frogs alone.

“The discovery of such a distinctive species within a comparatively well-studied park points towards the gaps in our knowledge of the amphibians of the tropics. It also highlights the role that bad weather, especially cyclones, can play in bringing otherwise hidden frogs out of hiding — Rhombophryne ellae was caught just as Cyclone Ava was moving in on Madagascar, and several other species my colleagues and I have recently described were also caught under similar cyclonic conditions,” says Dr. Scherz.

The species is known so far only from a single specimen, making it difficult to estimate its conservation status. Yet, based on the status of other, related frogs from the same area, it will probably be Red-listed as Near Threatened due to its presumably small range and micro-endemicity.

Pinetum plants, birds and tadpoles


This 2017 video is about Pinetum Blijdenstein in Hilversum, the Netherlands. This botanical garden was founded in 1898.

We went there today. In the middle is a pond, called the ‘Mesozoic pond’. Around it, all plants are relatives of plants that already lived during the age of dinosaurs. Like ferns, horsetails and conifers. Flowering plants had just started then. Around the pond is just one flowering plant species, a magnolia. Magnolias are relatives of plants that already lived during the Cretaceous.

In the pond, tadpoles swam.

Sounds of great spotted woodpecker, blackbird and robin. A song thrush sings, another one feeds on a lawn.

Then, we went to the Costerustuin botanical garden.

This 2008 video is about the Costerustuin.

The garden also has a pond; smaller than the pinetum pond and not Mesozoic.

Tadpoles swam, and pondskaters skated on the surface.

A great tit on a tree.

After we left, a blackcap sang.