Animal News Stories

1 06, 2022

Have we Got Evolutionary Trees All Wrong?

By Mike|2022-10-21T10:12:56+01:00June 1st, 2022|Adobe CS5, Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Main Page|0 Comments

A study led by scientists at the Milner Centre for Evolution at the University of Bath suggests that a fundamental cornerstone of evolutionary biology could be misrepresenting taxonomic relationships.

It is usual practice for biologists to establish evolutionary trees that set out the relationships between organisms. New research published in the academic journal “Communications Biology”, suggests that most of the evolutionary trees that have been constructed could be inaccurate and that convergent evolution is much more common than previously thought.

Mammal tree of life. — The mammalian tree of life. New research indicates that trees constructed using genetic data (where available) will be more accurate than trees built using anatomical comparisons. Picture credit: Mario dos Reis Barros and Sandra Alvarez-Carretero.

These trees are constructed by comparing anatomical characteristics, but this research suggests evolutionary trees based on the analysis of genetic sequences may be more reliable.

Overturning Centuries of Scholarly Work

Since Charles Darwin erected a “tree of life” in the 19th century, biologists have been trying to develop “family trees” of organisms by carefully examining differences in their anatomy and morphology.

With the development of rapid genetic sequencing techniques, scientists are now able to use genetic (molecular) data to compile evolutionary relationships very quickly and cheaply.

This genetic approach has led to substantial revisions in our understanding. Organisms once thought to be closely related have been demonstrated to belong to very different branches of the evolutionary tree.

Comparing the Two Methods of Building Evolutionary Trees

Scientists at the University of Bath compared evolutionary trees based on a traditional analysis of anatomy/morphology with those created using molecular data. The researchers discovered that the animals grouped together by molecular trees lived more closely together geographically than the animals grouped using the morphological trees, which implies that genetic themed evolutionary trees are more accurate.

Commenting on the significance of this study, one of the co-authors, Matthew Wills, Professor of Evolutionary Paleobiology at the Milner Centre for Evolution (University of Bath) explained:

“It turns out that we’ve got lots of our evolutionary trees wrong. For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story. Our study proves statistically that if you build an evolutionary tree of animals based on their molecular data, it often fits much better with their geographical distribution.”

Biogeography – A Reliable Guide to Evolutionary Relationships

Where organisms live, their biogeography, is regarded as an important source of evolutionary evidence that was familiar to 19th century scientists such as Darwin, Owen and Huxley. Genetic studies of animals that bear little similarity to each other such as aardvarks, elephants, golden moles, manatees and elephant shrews demonstrate that they originated from the same branch of the mammalian family tree. Molecular studies place these mammals into a single group called the Afrotheria, so-named because these animals seem to have originated from Africa, so the molecular data matches the biogeography.

An African elephant model. — An African elephant (Loxodonta). Molecular analysis has constructed trees showing that elephants, golden moles, elephant shrews and swimming manatees have all originated from the same branch of the mammalian family tree, although they look very different to each other and occupy different roles in the ecosystem.

Convergent Evolution More Prevalent

The study also found that convergent evolution was more prevalent than previously thought. Convergent evolution occurs when a trait or characteristic evolves separately in two genetically unrelated groups of organisms such as the evolution of tail flukes in cetaceans and the entirely unrelated ichthyosaurs.

Professor Wills added:

“We already have lots of famous examples of convergent evolution, such as flight evolving separately in birds, bats and insects, or complex camera eyes evolving separately in squid and humans. But now with molecular data, we can see that convergent evolution happens all the time, things we thought were closely related often turn out to be far apart on the tree of life.”

Ichthyosaur compared to a cetacean. — *An example of convergent evolution. Although unrelated, ichthyosaurs and cetaceans are similar in their appearance.*

The Professor explained that people who make a living as celebrity doubles or lookalikes are not usually related to the person that they are impersonating. Individuals in a family do not always look the same, it is the same for evolutionary trees.

Professor Wills stated:

“It proves that evolution just keeps on re-inventing things, coming up with a similar solution each time the problem is encountered in a different branch of the evolutionary tree. It means that convergent evolution has been fooling us, even the cleverest evolutionary biologists and anatomists for over a hundred years!”

Everything Dinosaur acknowledges the assistance of a media release from the University of Bath in the compilation of this article.

The scientific paper: “Molecular phylogenies map to biogeography better than morphological ones” by Jack W. Oyston, Mark Wilkinson, Marcello Ruta and Matthew A. Wills published in Communications Biology.

27 04, 2022

21% of All Reptiles Threatened with Extinction

By Mike|2023-02-08T08:35:13+00:00April 27th, 2022|Adobe CS5, Animal News Stories, Key Stage 3/4, Main Page, Teaching|0 Comments

One in five species of reptile is threatened with extinction. A team of international scientists including researchers from the Zoological Society of London, the University of Witwatersrand (Johannesburg, South Africa), Monash University (Victoria, Australia) and the Biodiversity Assessment Unit, IUCN-Conservation International based in Washington DC (USA), have conducted a comprehensive extinction-risk assessment of the class Reptilia. Writing in the academic journal “Natural” the team conclude that at least 1,829 out of 10,196 species of reptile (21.1%) are threatened.

Saltwater crocodile (Estuarine crocodile). — A Saltwater crocodile (Crocodylus porosus). The researchers conclude that crocodilians and turtles are particularly vulnerable to extinction. The study suggests more than half of crocodiles and almost two thirds of turtles are threatened with extinction.

Agriculture, Logging, Urban Development and Invasive Species

A global assessment of the risk of extinction to species of reptile has been lacking, although similar studies have been undertaken for the other tetrapods such as amphibians, mammals and birds. The researchers conclude that reptiles are threatened by the same major factors that threaten other tetrapods— agriculture, logging, urban development and invasive species, although the threat posed by climate change remains uncertain. Many species of reptile live in extremely arid or desert regions, this comprehensive study reveals that it is those reptiles that live in forests that face the greatest threat.

Is the skull that of a lizard? — *An Anolis lizard, reptiles that live in forested areas are the most threatened according to a comprehensive study published in the journal Nature.*

Reptiles Threatened with Extinction

The scientists discovered that birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles. The study revealed that efforts to conserve other threatened tetrapods (mammals, birds and amphibians) are more likely than expected to co-benefit many threatened species of reptile. Although reptiles are well known to inhabit arid habitats such as deserts and scrubland, most reptile species occur in forested habitats, where they and other vertebrate groups, suffer from threats such as logging and conversion of forest to agriculture. The study found that 30% of forest-dwelling reptiles are at risk of extinction, compared with 14% of reptiles in arid habitats.

Radiated Tortoise (Astrochelys radiata). — *The Radiated tortoise (Astrochelys radiata), native to Madagascar is critically endangered due to habitat loss and poaching. Picture credit: IUCN/Anders G. J. Rhodin.*

An Urgent Multifaceted Plan is Needed

Neil Cox, co-leader of the study and Manager of the IUCN-Conservation International Biodiversity Assessment Unit in Washington DC stated:

“The results of the Global Reptile Assessment signal the need to ramp up global efforts to conserve them. Because reptiles are so diverse, they face a wide range of threats across a variety of habitats. A multifaceted action plan is necessary to protect these species, with all the evolutionary history they represent.”

South American marked gecko (Homonota horrida). — *The South American marked gecko (Homonota horrida) is found in Paraguay and Argentina. Reptile species face a significant extinction threat. Picture credit: IUCN/ Ignacio Roberto Hernández.*

The report states that although some reptiles including most species of crocodiles and turtles require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.

Everything Dinosaur acknowledges the assistance of a media release from the International Union for Conservation of Nature (IUCN) in the compilation of this article.

The scientific paper: “A global reptile assessment highlights shared conservation needs of tetrapods” by Neil Cox, Bruce E. Young, Philip Bowles, Miguel Fernandez, Julie Marin et al published in Nature.

29 03, 2022

When Did the Beetles Take Over the World?

By Mike|2024-10-30T13:08:19+00:00March 29th, 2022|Adobe CS5, Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|1 Comment

Remarkably, one in four named animal species is a beetle. There are over 380,000 beetle species that have been scientifically described and perhaps several million more awaiting formal description. Members of the Order Coleoptera are distinguished from other insects as their front pair of wings are hardened into wing-cases (elytra) and they exploit a huge range of ecological niches and environments. However, their evolutionary origins remain uncertain and it is not known exactly when these six-legged animals became so numerous and specious.

Seventeen scientists including researchers from the University of Bristol have set about unravelling the evolutionary history of these amazing insects.

Permian beetle fossils and line drawings.

Examples of Permian beetles including fossilised wings and carapaces with (B and D) life reconstructions. Picture credit: NIGPAS.

Picture credit: NIGPAS

Mammoth Mathematical Models

A project to map the evolutionary history of arguably, the most successful and diverse animals of all time was a mammoth task. The researchers used a 68-gene character dataset that had been compiled previously which had sampled 129 out of the 193 recognised beetle families alive today and compared this to the beetle fossil record to provide a refined timescale of beetle evolution. A supercomputer at the University of Bristol’s Advanced Computing Research Centre slogged through the information for 18 months to produce the most comprehensive evolutionary tree of the Coleoptera ever created.

The mathematical models at the very heart of this research demonstrated that different beetle clades diversified independently, as various new ecological opportunities arose. There was no single, immense, all-encompassing divergence event.

One of the corresponding authors of the paper, published by Royal Society Open Science, Professor Chenyang Cai (University of Bristol) commented:

“There was not a single epoch of beetle radiation, their secret seems to lie in their remarkable flexibility. The refined timescale of beetle evolution will be an invaluable tool for investigating the evolutionary basis of the beetle’s success story”.

A beautifully preserved weevil fossil (Crato Formation).

Although beetle fossils are exceptionally rare, the research team used data from a total of 57 beetle fossils to help map the evolutionary development of the Coleoptera. The picture above shows the fossilised remains of a beetle from the Early Cretaceous of Brazil (Crato Formation). Picture credit: Museu Nacional.

Picture credit: Museu Nacional

Carboniferous Origins but the Evolution of Flowering Plants had Little Impact

The oldest beetle fossils date back to around 295 million years ago (Early Permian), molecular clock studies indicate an origin in the Late Carboniferous. The analysis revealed that all the modern beetle suborders had originated by the Late Palaeozoic with a Triassic-Jurassic origin of most of the extant families.

It had been thought that as flowering plants became the dominant terrestrial plants in a period referred to as the Cretaceous Terrestrial Revolution (KTR), so beetles diversified to take advantage of new ecological niches as the angiosperms evolved. However, this study concludes that the major beetle clades were present before the KTR. Nevertheless, some scarabaeoid and cucujiform clades underwent diversification during the Late Jurassic to Early Cretaceous, partly overlapping with the diversification of major angiosperms clades in the Early to mid-Cretaceous.

However, the previously postulated strong link between flowering plant evolution and the rapid expansion of the beetle suborder is refuted by this research.

Newly published research concludes that the rise of the flowering plants did not result in a substantial expansion of the Coleoptera. Picture credit James McKay.

Picture credit: James McKay

Advances in Technology and Genetics

Professor Cai explained that this research into the Coleoptera would not have been possible without advances in computer technology and genetics. He stated:

“Reconstructing what happened in the last 300 million years is key to understanding what gave us the immense diversity beetles are known for today”.

Everything Dinosaur acknowledges the assistance of a media release from the University of Bristol in the compilation of this article.

The scientific paper “Integrated phylogenomics and fossil data illuminate the evolution of beetles” by Chenyang Cai, Erik Tihelka, Mattia Giacomelli, John F. Lawrence, Adam Ślipiński, Robin Kundrata, Shûhei Yamamoto, Margaret K. Thayer, Alfred F. Newton, Richard A. B. Leschen, Matthew L. Gimmel, Liang Lü, Michael S. Engel, Patrice Bouchard, Diying Huang, Davide Pisani and Philip C. J. Donoghue published in Royal Society Open Science.

The Everything Dinosaur website: Prehistoric Animal Models.

17 03, 2022

A New Batch of Frogspawn Spotted in the Pond

By Mike|2024-10-28T13:57:12+00:00March 17th, 2022|Animal News Stories, Main Page, Photos|0 Comments

Yesterday, March 16th (2022), a new batch of frogspawn was spotted in the office pond. This spawning has occurred a fortnight after the first frogspawn was observed. Team members at Everything Dinosaur think it is unusual for there to be such a protracted spawning season for the frogs in our area (Rana temporaria).

A new batch of frogspawn on March 16th 2022.

The newly laid frogspawn has been highlighted with a red circle. It is pleasing to note that such a large amount of frogspawn has been laid, indicating a healthy frog population. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

2022 Spawning Season

The first frogspawn was observed on the morning of March 2nd, the following day much more frogspawn was laid and team members counted as many as seven frogs in the pond.

The exact amount of frogspawn is difficult to calculate as it tends to congeal into a single mass (making predation and consumption difficult). However, it was estimated on the 3rd March that perhaps seven or eight batches of spawn had been produced. The frog species is the Common frog (Rana temporaria). In 2021, frogs spawned around the 11th of March, in 2020, the spawning occurred around the 22nd of the month. Team members have kept a record of the time of spawning over the last decade or so, for example, in 2018 frogspawn was spotted on the 17th of March, whilst in 2017 spawning occurred six days earlier.

The frogspawn laid on the 16th was produced 14 days later than the first batch. We are not sure why spawning has taken place over two weeks, we have not recorded this protracted spawning previously.

More frogspawn laid in the office pond (16th March 2022).

A closer view of the newly laid frogspawn discovered on Wednesday 16th March. The first frogspawn was spotted on the morning of the 2nd of March, on the 3rd of March several more batches of eggs were laid. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

It is pleasing to note that such a large amount of frogspawn has been laid. This indicates a healthy frog population in the local area.

The timing of events such as seasonal spawning can be used as an indicator of climate change, it is likely that as our planet continues to warm events such as frogs spawning will occur earlier in the spring.

Visit the Everything Dinosaur website: Dinosaur Toys.

3 03, 2022

Frogspawn in the Office Pond (2022)

By Mike|2024-10-28T13:59:50+00:00March 3rd, 2022|Animal News Stories, Main Page, Photos|2 Comments

We have frogspawn in the office pond! On the morning of Wednesday March 2nd, a single batch of frogspawn was spotted in the office pond. A frog had been seen in the pond a few days earlier so team members were optimistic that spawning activity was imminent. We suspect that the first batch of spawn was laid in the early morning of the 2nd of March.

The first frogspawn of 2022 (March 2nd 2022)

The first batch of frogspawn was laid early in the morning of the 2nd March 2022.

Picture credit: Everything Dinosaur

Seven or Eight Batches of Frogspawn

The following morning several more batches of frogspawn were spotted. In total, Everything Dinosaur team members counted seven frogs in the pond. The exact number of batches of frogspawn is difficult to calculate as the batches have been concentrated into a single area of the office pond. However, it has been estimated that there are around seven or eight batches of spawn. All the frogs are Common frogs (Rana temporaria). In 2021, frogs spawned in the office pond around the 11th of March, in 2020, it was later still around the 22nd of March.

Much more frogspawn was laid on the 3rd March. The frogs have spawned a week earlier than in 2021.

Picture credit: Everything Dinosaur

We shall keep watching the office pond to see if any more spawn is laid in the coming days. We look forward to the spawn hatching and observing the progress of the tadpoles.

Visit the award-winning Everything Dinosaur website: Dinosaur Toys and Models.

16 01, 2022

Dating the Mammal Tree of Life

By Mike|2024-10-14T12:06:57+01:00January 16th, 2022|Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Recently published research has answered an important question regarding the timing of the evolutionary origins of modern types of placental mammals such as the Carnivora, the rodents and the primates. Once the non-avian dinosaurs vanished some 66 million years ago, placental mammals rapidly evolved and diversified to fill many of the niches in ecosystems vacated by the extinct members of the Dinosauria. Researchers have shed light on the tree of life.

Researching the Mammalian Tree of Life

The research team who included scientists from Queen Mary University of London, Cambridge University, University College London, the University of Bristol and Imperial College London used a new and fast Bayesian statistical approach to plot the timeline of mammal evolution. The data generated confirms the hypothesis that although the first placental mammals evolved in the Mesozoic, it was only after the KPg extinction event that marked the end of this Era and the beginning of the Cenozoic, some 66 million years ago, that the ancestors of today’s modern placental mammal groups evolved.

The research team used a new and rapid Bayesian statistical approach to plot the timeline of mammal evolution. The data generated confirms the hypothesis that although the first placental mammals evolved in the Mesozoic, it was only after the KPg extinction event that marked the end of this Era and the beginning of the Cenozoic, that the ancestors of today’s modern placental mammal groups evolved. Picture credit: Mario dos Reis Barros and Sandra Alvarez-Carretero.

Picture credit: Mario dos Reis Barros and Sandra Alvarez-Carretero

Analysing the Mammalian Genomic Dataset

Writing in the academic journal “Nature”, the scientists used a novel Bayesian statistical method to analyse an enormous mammal genomic dataset, in a bid to plot more precisely the timeline of the evolution of modern mammals. They conclude that the ancestors of these modern groups postdate the KPg extinction event.

The Bayesian analysis had to be robust, not only to handle the genetic data from almost 5,000 mammal species and 72 complete genomes but also to accommodate and account for uncertainties within the huge amount of data being processed.

Tracing the mammalian family tree. Picture credit: Luo Laboratory.

Picture credit: Luo Laboratory

Tackling a Contentious Topic in Evolutionary Biology

Commentating on the significance of this study, one of the co-authors of the paper, Professor Philip Donoghue (Bristol University) stated:

“The timeline of mammal evolution is perhaps one of the most contentious topics in evolutionary biology. Early studies provided origination estimates for modern groups deep in the Cretaceous, in the dinosaur era. The past two decades had seen studies moving back and forth between post- and pre-KPg diversification scenarios. Our precise timeline settles the issue.”

The statistical method developed for this study can be used to help resolve other controversial areas of research that require the detailed analysis of huge amounts of data. The scientists are confident that this technique can be applied to even grander projects such as the Earth BioGenome project which aims to plot a reliable evolutionary timescale for the development of life on Earth.

Everything Dinosaur acknowledges the assistance of a media release from the University of Bristol in the compilation of this article.

The scientific paper: “A Species-Level Timeline of Mammal Evolution Integrating Phylogenomic Data” by Sandra Álvarez-Carretero, Asif U. Tamuri, Matteo Battini, Fabrícia F. Nascimento, Emily Carlisle, Robert J. Asher, Ziheng Yang, Philip C. J. Donoghue and Mario dos Reis published in the journal Nature.

Visit Everything Dinosaur’s website: Everything Dinosaur.

14 09, 2021

Modern Snakes Evolved from a Handful of Species

By Mike|2024-07-02T21:46:08+01:00September 14th, 2021|Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Key Stage 3/4, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

New research published in the journal “Nature Communications” suggests that all extant snakes evolved from just a handful of species that survived the K-Pg extinction event 66 million years ago. The researchers conclude that this catastrophic extinction event, that wiped out the non-avian dinosaurs and something like 75% of all terrestrial life, was a form of “creative destruction” leading to a burst of evolutionary development within the Serpentes.

*Snakes benefitted from the End-Cretaceous extinction event. It enabled them to evolve rapidly and to exploit new, ecological niches. Picture credit: Joschua Knüppe.*

Snakes benefited from the extinction event, the loss of so many competitors allowed them to diversify rapidly and to occupy new niches in food chains.

The Snake Fossil Record

The fossil record of snakes is relatively poor because snake skeletons are typically small and fragile making the preservation of fossil material a rare event.

It is generally accepted that snakes (Suborder Serpentes), evolved from lizards. Snakes gradually losing their limbs, whether the first snakes were burrowers and evolved from burrowing lizards or whether the first snakes were adapted to a life in marine environments is an area of on-going debate between vertebrate palaeontologists. For example, in 2016 a team of scientists challenged the conclusions from the paper that described Tetrapodophis amplectus, a primitive snake-like animal from the Lower Cretaceous of Brazil. It had been suggested that T. amplectus, which had been described and named the year before, was adapted to a life underground, however, researchers from Canada and Australia challenged this view and proposed a marine habit for this 20 cm long animal that has been classified as being close to the base of the evolutionary lineage of true snakes.

Tetrapodophis Illustrated — *The tiny limbs of Tetrapodophis may have been used to hold prey. Scientists are uncertain whether this animal was a burrower or adapted to a marine environment. Picture credit: Julius Csotonyi.*

To read more about this research: Were the Very First Snakes Marine Reptiles?

Studying Fossils and the Genomes of Living Snakes

The research, led by scientists at the University of Bath in collaboration with researchers from Cambridge, Bristol and Germany, involved examining snake fossils and an analysis of the genomes of living snakes to pinpoint genetic differences permitting a picture of modern snake evolution to be built up.

The results indicate that despite the great variety of snakes alive today – cobras, vipers, pythons, boas, sea snakes and blind, burrowing snakes for example, all extant snakes can be traced back to a handful of species that survived the K-Pg extinction event that took place 66 million years ago.

Snake Survival Strategy

The authors postulate that the ability of snakes to shelter underground and go for long periods without food helped them survive the destructive effects of the bolide impact event. In the aftermath, the extinction of their competitors including Cretaceous snakes and small theropod dinosaurs, permitted snakes to move into new niches, new habitats and new parts of the world. Today, snakes are found in all but the highest latitudes and are present on every continent except Antarctica.

The researchers, which included lead author Dr Catherine Klein, a former graduate of Bath University but now based at the Alexander-Universität Erlangen-Nürnberg (FAU) in Germany, state that modern snake diversity – including tree snakes, sea snakes, venomous vipers and cobras, and huge constrictors like boas and pythons – emerged only after the non-avian dinosaur extinction.

Dr Klein commented:

“It’s remarkable, because not only are they surviving an extinction that wipes out so many other animals, but within a few million years they are innovating, using their habitats in new ways.”

A Change in Snake Vertebrae

Fossils also show a change in the shape of snake vertebrae in the aftermath, resulting from the extinction of Cretaceous lineages and the appearance of new groups, including giant sea snakes, such as Gigantophis garstini from the Eocene of northern Africa which may have reached a length of ten metres. Gigantophis was scientifically described in 1901, it was thought to have been the largest snake to have ever lived, until in 2009 when the giant, South American boa – Titanoboa cerrejonensis was described.

*The Rebor Titanoboa Museum Class Maquette Monty Resurgent. A model of the largest snake known to science.*

The picture (above) shows the Rebor Titanoboa Museum Class Maquette known as Monty Resurgent.

To view the Rebor range of models and figures: Rebor Prehistoric Animal Models.

Rapidly Spreading Around the Globe

The research team also suggest that snakes began to spread rapidly around the globe. The “Greenhouse Earth” conditions that occurred close to the boundary between the Palaeocene and Eocene Epochs that led to the establishment of extensive tropical forests in the Northern Hemisphere, would have facilitated the geographical spread of cold-blooded animals such as snakes.

Although the ancestor of living snakes probably lived somewhere in the Southern Hemisphere, snakes first appear to have spread to Asia after the extinction event.

Corresponding author, Dr Nick Longrich, from the Milner Centre for Evolution (University of Bath), explained:

“Our research suggests that extinction acted as a form of “creative destruction”- by wiping out old species, it allowed survivors to exploit the gaps in the ecosystem, experimenting with new lifestyles and habitats. This seems to be a general feature of evolution – it’s the periods immediately after major extinctions where we see evolution at its most wildly experimental and innovative. The destruction of biodiversity makes room for new things to emerge and colonise new landmasses. Ultimately life becomes even more diverse than before.”

Further Serpentes Evolution Driven by Climate Change

The researchers also found evidence for a second major diversification event around the time that the world shifted from a warm and moist climate to a colder, more seasonal climate (Oligocene Epoch).

It seems, that for the snakes at least, global catastrophes can have their upsides. The patterns seen in snake evolution hint at the key role played by mass extinction events – they are the catalysts for driving rapid evolutionary changes.

The scientific paper: “Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction” by Catherine G. Klein, Davide Pisani, Daniel J. Field, Rebecca Lakin, Matthew A. Wills and Nicholas R. Longrich published in Nature Communications.

20 05, 2021

Amazing Horned Crocodile Gets a Home

By Mike|2024-05-26T10:30:27+01:00May 20th, 2021|Animal News Stories, Key Stage 3/4, Main Page, Photos/Pictures of Fossils|0 Comments

Specimens of a strange, recently extinct crocodile housed at the American Museum of Natural History (New York), have helped unravel a mystery surrounding the evolutionary relationships of crocodilians. The skulls belong to the horned crocodile of Madagascar (Voay robustus) and a research team has demonstrated that it was closely related to “true crocodiles” – Crocodylus, making it the closest species to the common ancestor of the crocodile genus.

Voay robustus - horned crocodile skull — *A skull of Voay robustus collected at Ampoza during the joint mission Franco-Anglo-American expedition from 1927–1930 (White, 1930). Picture credit: Hekkala et al.*

Recently Extinct

When the first Europeans came to Madagascar the native Malagasy people told them about two distinct types of crocodiles that lived on their island. There was a gracile form that preferred rivers, this was identified as a population of Nile crocodiles (Crocodylus niloticus), but the swamps and lakes were home to a crocodile that the early explorers had never seen before. This second type was a much more heavy-set and powerful animal with two, bony bumps at the top of its skull.

When first named and described in 1872 (Grandidier and Vaillant), it was thought to be a species of true crocodile – a member of the Crocodylus genus. More recent studies have suggested affinities with the dwarf crocodiles (Osteolaeminae), however, with an estimated length of around 5 metres V. robustus was much larger than any other species assigned to this group.

New research published in the academic journal Communications Biology, which used DNA extracted from the American Museum of Natural History specimens, has resolved the phylogeny of this enigmatic reptile. Carbon dating of the material used in the study confirms that the horned crocodile probably survived until just a few hundred years ago.

Voay robustus phylogeny — *The DNA study places the horned crocodile right next to the true crocodile branch of the evolutionary tree, making it the closest species to the common ancestor of the crocodiles alive today.*

One of the authors of the scientific paper, Evon Hekkala, a research associate at the American Museum of Natural History stated:

“This crocodile was hiding out on the island of Madagascar during the time when people were building the pyramids and was probably still there when pirates were getting stranded on the island. They blinked out just before we had the modern genomic tools available to make sense of the relationships of living things. And yet, they were the key to understanding the story of all the crocodiles alive today.”

Mitochondrial DNA extracted from sub-fossil specimens found during a Franco-Anglo-American expedition to south-western Madagascar (1927 to 1930), demonstrates that V. robustus was not a true crocodile but very closely related to that lineage that led to them. Being placed next to the true crocodiles on an evolutionary tree suggests that it was the closest species to the common ancestor of extant members of the Crocodylus genus.

Voay robustus lower jaw. — The tip of the lower jaw (dentary) of the horned crocodile from Madagascar (Voay robustus). Carbon dating of the subfossils suggests that they are less than 1,400 years old. Picture credit: The American Museum of Natural History.

Co-author George Amato, (American Museum of Natural History), explained:

“This is a project we’ve tried to do on and off for many years, but the technology just hadn’t advanced enough, so it always failed. But in time, we had both the computational setup and the paleogenomic protocols that could actually fish out this DNA from the fossil and finally find a home for this species.”

“Teasing apart the relationships of modern crocodiles is really difficult because of the physical similarities,” Hekkala added. “Many people don’t even realise that there are multiple species of crocodiles, and they see them as this animal that’s unchanging through time. But we’ve been trying to get to the bottom of the great diversity that exists among them.”

Surprising Results

The close affinity of Voay to Crocodylus lends weight to the idea that Crocodylus originated in Africa and then dispersed into the Americas and Asia/Australia. Competing theories have proposed an Asian origin for Crocodylus but as Voay was restricted to Madagascar and has been cited as the closest species to the true crocodiles, this DNA analysis lends weight to the “African origins” idea.

The scientific paper: “Paleogenomics illuminates the evolutionary history of the extinct Holocene “horned” crocodile of Madagascar, Voay robustus” by E. Hekkala, J. Gatesy, A. Narechania, R. Meredith, M. Russello, M. L. Aardema, E. Jensen, S. Montanari, C. Brochu, M. Norell and G. Amato published in Communications Biology.

The Everything Dinosaur website: Everything Dinosaur.

8 05, 2021

Crocodile Conservation a Remarkable Success Story at Zoo Miami

By Mike|2024-05-26T09:17:13+01:00May 8th, 2021|Adobe CS5, Animal News Stories, Main Page|0 Comments

Zoo Miami (Florida), has announced that a clutch of Orinoco crocodile eggs has successfully hatched. The Orinoco crocodile (Crocodylus intermedius), is one of the world’s rarest crocodilians, in the wild, this species is limited to freshwater habitats in Venezuela and Columbia. As such, it is the most southerly of all the American crocodilians.

Crocodile Conservation Success

The female Orinoco crocodile laid a clutch of 45 eggs on February 5th (2021). Zoo staff collected the eggs and placed them in two incubators set at different temperatures. The sex of crocodilians is determined by the temperature that the eggs are incubated at. So, in order to ensure a mix of males and females, the clutch was divided in two and incubated in two batches.

Generally, cooler temperatures produce females and warmer temperatures produce males. By incubating the eggs in separate incubators with different temperatures, the curators at the crocodilian enclosure planned to have a mix of both males and females hatching in a bid to maximise the future breeding potential of the progeny.

A quartet of Orinoco crocodiles. — *Recently hatched, critically endangered Orinoco crocodiles are shown to the media. Picture credit: Zoo Miami.*

Hatching Spread over Several Days

The first eggs began to hatch on May 2nd, the mother of the brood, was herself hatched at Zoo Miami in 1980 and had been sent to various institutions before returning to the zoo two years ago. The father was hatched at the Dallas World Aquarium in the spring of 2004 and arrived at Zoo Miami in November 2006. This is their first clutch together.

A spokesperson for the zoo stated that once the crocodiles were big enough, it was hoped that these rare reptiles could be returned to the wild.

Zoo Miami (also known as The Miami-Dade Zoological Park and Gardens), was formed in 1948 and is the largest zoo in Florida and the fifth biggest in the United States. It is home to more than 3,000 animals, many of which such as the Orinoco crocodiles, are critically endangered.

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3 04, 2021

Extra-terrestrial End-Cretaceous Impact Gave Rise to the Amazon Rainforest

By Mike|2024-05-25T08:26:51+01:00April 3rd, 2021|Adobe CS5, Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Key Stage 3/4, Main Page, Palaeontological articles|0 Comments

The Amazon rainforest is an extremely important low latitude habitat with a huge diversity of animals, fungi and plant species. Described as the “lungs of the planet”, this tropical rainforest is at the very centre of many global conservation efforts. New research suggests that it was the extra-terrestrial impact event some 66 million years ago that led to the rise of this angiosperm dominated ecosystem.

K/Pg Extinction Event

Approximately 66 million years ago a rock from space smashed into our planet. This triggered a sudden mass extinction event devastating around 75% of all the animal and plant terrestrial species, many of which subsequently became extinct. At this time the dinosaurs, their cousins the pterosaurs and the majority of marine reptiles died out.

Analysis of Fossil Pollen and Study of Fossil Leaves

Writing in the journal “Science”, researchers from the Southern Methodist University (Texas) and the University of Wyoming report on the study of tens of thousands of fossil pollen specimens along with thousands of leaf fossils from Cretaceous-aged strata and deposits laid down after the K/Pg extinction event. The scientists, which include co-author Dr Ellen Currano (Department of Botany, University of Wyoming), found that the types of plant creating tropical forests were very different pre and post the extra-terrestrial impact. In the Late Cretaceous tropical forests were dominated by conifers and they were much more open than the dense, angiosperm forests that came about during the Palaeocene.

Cretaceous maniraptora. — Study suggests the floral composition of tropical rainforests changed dramatically after the extra-terrestrial impact event. During the Late Cretaceous tropical forests were dominated by conifers and forest canopies were less dense. Picture Credit: Danielle Dufault.

A Thick Forest Canopy Denying Access to Light

The scientists discovered that the fossil pollen and leaves show a marked transition in tropical forest flora. After the extra-terrestrial impact forests developed a thick canopy blocking much of the light from reaching the ground and angiosperms became more dominant.

How Did These Changes Come About?

As well as the documenting the turnover in flora and the transition from one tropical forest environment to a different type of rainforest in the Palaeocene, the researchers propose three possible explanations for this change:

The absence of large megaherbivores, specifically dinosaurs allowed plant densities in forests to increase. The extinction of giant plant-eating dinosaurs such as the Ceratopsia, hadrosaurs, armoured dinosaurs and the titanosaurs allowed plants to grow at lower levels as they were not being trampled or consumed by herbivorous dinosaurs.
Several types of fern and conifer became extinct during the K/Pg transition permitting new types of angiosperm (flowering plants) to evolve and exploit the vacated niches.
Falling ash from the impact enriched soils throughout the tropics, provided an advantage to faster-growing angiosperms.

The scientists conclude that the three hypotheses are not mutually exclusive and that a combination of factors could have led to the change in the flora as recorded in the fossil record.

A Significant Lesson for Today

Today, a rapidly changing climate, largely caused by the actions of our own species is having a dramatic effect on the world’s forests. The researchers note that the fossil record demonstrates that rainforests do not simply “bounce back”, after a catastrophe. They can take millions of years to recover and a very different type of ecosystem is likely to emerge.

The scientific paper: “The impactful origin of neotropical rainforests” by Bonnie F. Jacobs and Ellen D. Currano published in the journal Science.

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