Tooth scratches reveal new clues to pterosaur diets

The feeding habits of these prehistoric reptile species have remained largely elusive until now.

John Pickrell

PDF version

Wear and tear on fossil teeth of Dimorphodon macronyx (illustration) reveal it likely ate insects and small land vertebrates.Credit: Mark P. Witton/CC BY 4.0

Microscopic scratches on fossil teeth are forcing palaeontologists to rethink some cherished ideas about the diets of pterosaurs — flying reptiles that ruled the skies while terrestrial dinosaurs flourished on the lands beneath them.

Since they first uncovered pterosaur fossils in the eighteenth century, researchers have made assumptions about their eating habits, mostly on the basis of indirect clues such as the shapes of their teeth and the environments they lived in. But Jordan Bestwick, a palaeontologist at the University of Leicester, UK, and his colleagues sought more direct evidence: they performed the first examination of fossilized pterosaur teeth for tiny abrasions caused by food. Microscopic scratches and chips create characteristic surface textures that vary according to an animal’s diet, says Bestwick.

The preliminary findings are offering new evidence on the feeding habits of some species, and confirm theories about the diets of others. The results, which will form part of Bestwick’s PhD thesis, were presented at the Palaeontological Association annual meeting in London on 18 December.
One surprise in the analysis raised questions about the pterosaur Dimorphodon macronyx, which researchers assumed had hunted fish. The wear and tear on the reptile’s teeth now suggests it actually feasted on insects and land vertebrates.

Dental discoveries

Although pterosaurs existed for 150 million years, complete fossils are relatively rare and gut contents have been recovered from just four species. That means that most hypotheses about species’ diets have been “little more than speculation based on scant evidence”, says Bestwick.
He and his colleagues have so far examined 11 pterosaur species, looking at tooth specimens held at institutions such as the Natural History Museum in London and the Museum for Natural History in Berlin.

They used infinite-focus microscopes to create 3D images of tooth wear. They then used statistical methods to look at wear patterns in pterosaurs alongside the teeth of living species of bats, lizards and crocodilians that are known to eat insects or fish and other vertebrates. “We use that as our proxy data set to project the microwear of extinct organisms,” says Bestwick.

A Dimorphodon macronyx specimen at the Natural History Museum in London.Credit: Jordan Bestwick

Analysis of the pterosaur Rhamphorhynchus, first found in Germany in 1825, reveals wear patterns that are statistically similar to those seen in modern relatives of crocodiles called gharials, suggesting that Rhamphorhynchus also ate fish. This helps back up a long-standing hypothesis about the ancient reptile’s diet, Bestwick says. Wear patterns on the teeth of Pterodactylus, the first pterosaur ever described, in 1784, suggests it was an omnivore as some experts had also hypothesized, he adds.
Stephen Brusatte, a palaeontologist at the University of Edinburgh, UK, says the study is one of the first attempts to use a rigorous statistical method to determine what these flying reptiles ate. “This is a great example of how a combination of cutting-edge techniques and careful comparisons to modern species can help us understand how long-extinct animals behaved,” says Brusatte.

Steven Vidovic, a vertebrate palaeontologist at the University of Portsmouth, UK, says complete fossils of pterosaurs are so rare because their light, hollow bones were relatively fragile and unlikely to fossilize. The lack of direct evidence of their diets has often led to assumptions about what they ate based on their environment, he says. For instance, pterosaur remains are often found in coastal environments, which led researchers to assume that many species ate fish, he says.

Changing views

Dimorphodon was previously believed to be a piscivore because people compared the shape of its head to those of modern puffins, which do eat fish, says Bestwick. Only in the past decade have researchers modelled its flight capabilities, with some concluding that it was a relatively poor flyer that couldn’t have effectively hunted fish, he says. Patterns of wear on the teeth of the four Dimorphodon macronyx fossils he has examined so far fit with his predictions for wear patterns produced by eating the insects and land vertebrates that lived alongside it early in the Jurassic period, around 190 million years ago.

More recent studies of pterosaur anatomy have also suggested that some species stalked their prey on land and ate insects, says Vidovic. “While there is good reason to think those lifestyles are likely, there was no way of independently testing the hypotheses.”
Vidovic says the latest analysis will allow palaeontologists to test theories on pterosaurs’ diets. “This new method presents a real opportunity to observe the hardness and abrasiveness of the food pterosaurs were consuming, and test hypotheses of ecology,” he says.

doi: 10.1038/d41586-018-00080-y

National Geographic: Big Cats - An Amazing Animal Family
National Geographic: Dinastia Felina





Áudio 

Citação

This is the story of one of the most successful family of predators on Earth—cats—and their epic rise to power. In this series, zoologist Patrick Aryee journeys around the world to some of the planet’s wildest places, unearthing the cat family’s wide and diverse family tree. From the majestic Siberian tiger, to the agile, tree-dwelling margay, we will see a rich variety of cat shapes, colours, and sizes. Today, there are some 37 different species of cats spanning jungle, mountains, deserts, and grasslands. They can jump higher, run faster, and climb better most groups of animals on Earth. Big Cats will reveal the amazing stories of how some of the most powerful cat dynasties came to be.

	Parte 01 Patrick começa sua busca com as famílias mais antigas das oito dinastias. Viajamos para as selvas da Tailândia para conhecer o felino mais velho vivo no planeta, o misterioso leopardo-nebuloso.
	Parte 02 Oito milhões de anos atrás os felinos se aventuraram nas Américas pela primeira vez. Para conquistar este vasto, novo e enorme continente eles se dividiram em três novas dinastias.

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Por que uma lei suíça quer proibir chefs de cozinhar lagostas vivas no país

13 Jan 2018

(atualizado 15/Jan 10h10)

Medida passa a vigorar a partir de março e também vale para outros crustáceos como caranguejos; país segue a Itália que também proibiu armazenamento do animal vivo em gel.

Foto: Tim Wimborne/Reuters

Lagostas não poderão ser mantidas em gelo para serem cozinhadas vivas

 A Suíça passou na quarta-feira (10) lei que proíbe restaurantes de preparar lagostas e outros crustáceos usando como técnica o cozimento em água fervente enquanto os animais ainda estão vivos. De acordo com a nova regra do país europeu, crustáceos deverão ser atordoados antes de ir para a panela.

A legislação ainda vai além e proíbe o transporte dos animais em gelo. “Espécies aquáticas devem sempre ser mantidas em seus ambientes naturais”, diz a lei que passa a valer a partir de março deste ano.

Essa última medida acompanha determinação da justiça italiana, de julho de 2017, que decidiu a favor de um grupo de proteção aos animais local contra um restaurante de Florença que mantinha lagostas vivas no gelo até o momento de serem cozinhadas.

“Enquanto o particular método de cozimento possa ser considerado legal por ser reconhecido como um costume, o sofrimento causado pelo armazenamento dos animais enquanto eles esperam para ser cozinhados não pode ser justificado da mesma forma”, apontou o juiz italiano. Como alternativa, aponta práticas já adotadas por restaurantes e supermercados de manter os animais em tanques de água oxigenados em temperatura ambiente.

Quanto à Suíça, de acordo com informações da rede pública local RTS, a nova lei exige que o atordoamento do animal seja feito por meio de choques ou “destruição mecânica” do cérebro do crustáceo.

Entre as razões apontadas para a prática de se cozinhar crustáceos vivos, há explicações que recaem sobre a textura e o sabor da carne do animal. Para o professor titular do departamento de zoologia da Unesp (Universidade Estadual Paulista), Adilson Fransozo, a explicação seria apenas um costume culinário motivado pela intenção de restaurantes em mostrar ao cliente que o produto preparado se trata de um animal fresco.

“Cozinhar o animal vivo é pura crueldade. Não tem razão para isso. Tanto é que a lagosta que o Brasil exporta, vai a parte do abdômen no gelo. O resto é jogado fora porque é tudo víscera. A prática da água quente é puro costume e ignorância”, diz ao Nexo.

Pacote animal

A lei suíça sobre os crustáceos vem acompanhada de um “pacote” que envolve outras leis que fortalecem a proteção animal no país. Além dela, o governo proibiu também a venda e uso de coleiras que soltam choque em cachorros visando condicioná-los a não latir, ou ainda regulações contra fazendas de criação de filhotes de cães e endurecimento de regras contra quem faz uso de animais em eventos públicos, como circos.

Contra sofrimento

Medidas contra o sofrimento de crustáceos são uma demanda de grupos de defesa de animais, como a Peta (People for the Ethical Treatment of Animals). Entre os argumentos, está o de que existem regulamentações que protegem outros animais como pássaros, mamíferos e répteis, mas não para crustáceos como lagostas e caranguejos.
“A pergunta que fica é: qual a diferença?”, disse o professor Robert Elwood, da Queens University, da Irlanda do Norte, à CNN. “Com todas as informações que temos, é muito certo que esses animais também sentem dor”. Elwood é um dos responsáveis por uma pesquisa, publicada em 2013 pelo periódico científico Journal of Experimental Biology que apontava para essa possibilidade.
Em um experimento, pesquisadores constataram que caranguejos-verde optavam repetidamente por abandonar abrigos escuros – ambiente preferido pela espécie – para não sofrerem choques dados pela equipe de Elwood.

Progressions- Evolution of Life

http://en.wikipedia.org/wiki/Eadweard_Muybridge#Stanford_and_horse_gaits

In 1878 the above sequence of images was taken by Eadweard Muybridge to settle a debate among horse racers--when a horse was galloping full speed, did they ever have all four legs off the ground?  The human eye alone was not fast enough to resolve the dispute.  Muybridge, the photographer who was called in, set up a sequence of cameras that would be set off by trip wires and found that horses are in fact completely air born at certain points within a full gallop. (Watch the video of this horse here.)

Based on these images alone, though, how do we know that the horse was actually running?  Couldn't the pictures have been of different horses?  Couldn't they have been jumping and not running?  This is more than just a thought experiment.  We're asking if it's justified to tie different pieces of information together to form a progression, just like we do in evolution.  Below we will explore several examples of biological progressions and ask what evidence there is that they represent evolutionary change over time.

Claim: Species have changed over time--descent with modification

Prediction: If evolution is true and species have changed over time, then we would expect there to be examples of this preserved in rock strata, across geography, in a lab, or in recorded history.

Falsification: Progressions of change across time do not exist.  Species are shown to be unchangeable.

Observations:  Fossil progressions, microevolution, biogeography (see examples below).

Corroboration: Dating techniques confirms the progression’s sequence. Multiple traits are held in common by the organisms showing relatedness.

Inference:  Provided with this gradual gradation in a trait we can infer that the species are related (though not necessarily direct descendants--evolution tends to meander).

Examples:

• Fossil progressions
  • The fossil record demonstrates not only large scale changes across time, phyla, but also within individual species.   Three particularly important features are represented within the fossil record.  Firstly, the species represented within the fossil record are often vastly different from the life of today.  Secondly, is that the the fossils are separately and distinctly layered.  Meaning, that we don’t find rabbit fossils in the Pre-Cambrian layers, nor dinosaurs mixed in with mammoths.  Lastly, both on the macro and micro scale of the fossil record we see trends of change that progress through time.

Whale evolution

http://evolution.berkeley.edu/evolibrary/article/evograms_03

Individual traits such as leg/pelvis position, nostril location, and ankle bones can also be traced back to the early artiodactyls that led to modern day whales.

http://www.bio.georgiasouthern.edu/bio-home/harvey/lect/lectures.html?flnm=evel&ttl=Evolution&ccode=el&mda=scrn

http://tinyfrog.wordpress.com/2008/02/01/pz-myers-vs-geoffrey-simmons-discovery-institute/

http://evolution.berkeley.edu/evolibrary/article/evograms_03

This is another image showing the homology between ancient whale ancestors (Pakicetus) and modern day even-toed ungulates (like pig and deer). Dogs were included on the far left as a contrast typical of non-even-toed ungulates.
http://www.bio.miami.edu/dana/160/160S13_5.html

   

http://scienceblogs.com/loom/2006/08/15/the-origin-of-the-ridiculous/

http://coastalpaleo.blogspot.com/2009_04_01_archive.html

http://scienceblogs.com/pharyngula/2006/05/23/no-genes-were-lost-in-the-maki/

The transition from toothed whale to baleen whale also has left transition fossils. This can be seen in the pattern of blood vessels on the roof of Aetiocetus weltoni's mouth that are highly similar to those used today to nourish the areas that produce the keratin baleen.

http://whyevolutionistrue.wordpress.com/2010/07/22/baleen-whales-a-lovely-transitional-form/
Original article: http://www.sdnhm.org/archive/research/paleontology/DemereMorphoBaleenTeeth.pdf

  Horse

http://www.mberg.com.au/dietary-changes-and-the-evolution-of-the-horse/

 

http://en.wikipedia.org/wiki/Evolution_of_the_horse

http://en.wikipedia.org/wiki/Evolution_of_the_horse

Tetrapod

http://evolution.berkeley.edu/evolibrary/article/evograms_02

We can even track individual traits, like skull bones and limb structure. Humans

http://evolution.berkeley.edu/evolibrary/article/evograms_07

http://media.hhmi.org/biointeractive/posters/2011%20human%20evolution.jpg

 

http://distraffscience.blogspot.com/2012/03/overview-of-human-evolution.html

   

http://www.pbs.org/wgbh/nova/evolution/adaptable-human.html

 

http://scienceblogs.com/laelaps/2007/10/23/troodon-sapiens-thoughts-on-th/

http://visual.ly/timeline-hominid-evolution

Notice the transition from long scapulas with oblique scapular spines good for arboreal climbing turned more horizontal as we began to climb and hang less.
http://openi.nlm.nih.gov/detailedresult.php?img=2860095_10764_2010_9399_Fig6_HTML&req=4http://www.sciencemag.org/content/338/6106/514.figures-onlyhttp://www.sciencemag.org/content/338/6106/478.figures-only

  Bird

http://evolution.berkeley.edu/evolibrary/article/evograms_06

http://www.nature.com/ncomms/journal/v2/n8/full/ncomms1437.html

http://palaeoblog.blogspot.com/2008/10/gene-expression-in-alligators-suggests.html

http://ncse.com/rncse/21/5-6/more-birds-dinosaurs

 

http://www.sciencemag.org/content/333/6049/1619.full

 

http://emilywilloughby.com/gallery/skeletals-and-diagrams/feather-evolution

A common evolutionary strategy to change the phenotype of a species is to change the developmental progression that leads to that phenotype. This diagram is showing how bird evolution progressed to have the adult phenotypes look like the juvenile phenotype of the ancestral species.
http://whyevolutionistrue.wordpress.com/2012/05/28/birds-may-be-paedomorphic-dinosaurs/
Also
http://www.nytimes.com/2012/06/05/science/skull-analysis-charts-the-changes-from-dinosaurs-to-birds.html?_r=0

Brachiopods

http://www.pnas.org/content/105/14/5430.figures-only

http://www.don-lindsay-archive.org/creation/eocoelia.html

Diatom

http://www.jstor.org/stable/4096816?origin=JSTOR-pdf
See pictures of diatom spines and valves to better understand what this graph represents: http://westerndiatoms.colorado.edu/taxa/species/stephanodiscus_yellowstonensis

Foraminifera

http://evolution.berkeley.edu/evolibrary/article/evograms_05

 

http://daphne.palomar.edu/ccarpenter/reptile%20to%20mammals.htm

Trilobites

 

Turtles

Read more: http://whyevolutionistrue.wordpress.com/2013/06/04/more-about-turtles/
Other resources:
http://whyevolutionistrue.wordpress.com/2013/06/02/turtle-origins/
And
http://www.elsevier.com/connect/how-the-turtle-got-its-shell-clues-revealed-by-fossils

Elephant

http://perlacopernik.wordpress.com/2012/08/11/the-mighty-elephant-the-real-king-of-the-savanna/
Also interesting:
http://www.sciencemag.org/content/334/6063/1699.figures-only
http://kozmopolitaydinlar.wordpress.com/2012/03/19/5508/fillerin-evrimi-2/

      Microevolution - There have been many instances where the observed change within a species is fast enough that it can be tracked by researchers.  Extending these trend lines into the future we can see how major adaptive changes can add up over time. Soapberry bugs

http://www.evolution-textbook.org/content/free/figures/03_EVOW_Art/08_EVOW_CH03.jpg

Three-spine stickleback fish

Summary: Put stickleback fish in a freshwater environment (they were transplants from salt water, but can survive in both) and over time they lose their protective, boney plates. They likely do so to conserve energy since their environment has different predatory pressures and less food during the winter.
http://www.sciencedaily.com/releases/2008/10/081010100457.htm

http://courseconnector.uoregon.edu/bi-131-intro-evolution

"Fig. 2. Evolution of lateral plate morph frequencies in Loberg lake between 1990 and 2007. Besides complete and low lateral plate morphs, we recognize three intermediate phenotypes described in Bell et al. (2004). These are "intermediate partials"(IP), partial morphs, and "intermediate lows"(IL). Notice that the frequency of the three intermediate phenotypes remained relatively low and constant throughout the time series."
http://life.bio.sunysb.edu/ee/belllab/loberg.html

Salmon

Pink salmon (Oncorhyncus gorbuscha) are getting smaller. Multiple reasons are possible but one is that fishermen have been consistently taking the largest, thus resulting in their reduced size through a form of artificial selection.
http://www.pbs.org/wgbh/evolution/library/10/3/l_103_02.html

Bacteria: Because of their short generation time, bacteria are excellent subjects to use for evolution experiments.  The longest running experiment is Richard Lenski's E. coli experiment. For some 60,000 generations the bacteria have been grown in a laboratory environment under controlled conditions and given very restrictive diets of sugars and nutrients.   At regular intervals the bacteria are sampled, frozen, and DNA sequenced.   Population growth, fitness, and body size are tracked over time.

http://www.evolution-textbook.org/content/free/figures/17_EVOW_Art/32_EVOW_CH17.jpg

Their average size also increase remarkably:

http://evolutionguide.wordpress.com/2011/11/10/the-best-of-the-lessons-of-evolution-the-longterm-e-coli-evolution-experiment/

  One of the most exciting finds of the study was the explosion of growth in one strain of bacteria that had multiple mutations that enable them to digest citrate in the presence of oxygen.  This ability resulted in the doubling of their population within their beaker.

http://www.nature.com/nature/journal/v489/n7417/full/nature11514.html

http://blogs.discovermagazine.com/gnxp/2009/10/the-arc-of-evolutionary-genetics-is-long/#.UkBbn9Jwpft

http://evolutionguide.wordpress.com/2011/11/10/the-best-of-the-lessons-of-evolution-the-longterm-e-coli-evolution-experiment/

  Flat periwinkle: The European green crab was introduced to the North Eastern coast of North America in the early 1800's.  These crabs started feeding on flat periwinkles by crushing them with their claws.  By comparing shells from museum specimens prior to the crab introduction to those of current day periwinkles a thickening of the shell was observed (conceivably due to the crab predation).  Subsequently, the natural selection process of thin shelled periwinkles was replicated in an experimental setting.

http://wps.prenhall.com/wps/media/objects/829/848975/EvoDotsTutorial.pdf

Samoan Blue Moon Butterfly (Hypolimnas bolina): A parasite common to arthropods called Wolbachia is passed through the female line in the egg.  To increase the parasite's chances of getting into the next generation of butterflies the parasite was killing off males.  This resulted in a drastically skewed population distribution with 99% of adults captured being female.  Over 4 years and 10 generations of butterfly the population re-established equilibrium with a 50:50 ratio of female to male.  Researchers believe this is due to the evolution of a repressor gene that inhibits the Wolbachia's biochemical attack. 

http://scienceblogs.com/grrlscientist/2007/07/16/samoan-butterflies-evolve-rapi/
Also:
http://www.livescience.com/1685-evolution-occurs-blink-eye.html
http://www.sciencemag.org/content/317/5835/214.full.pdf
http://www.sciencemag.org/content/317/5835/214.abstract

HIV: At this time the most common treatment for HIV are drug "cocktails," which are the combination of multiple drugs that combat HIV.  Isn't that a waste to use multiple drugs to fight one condition?  Not when evolution is taken into account.  HIV evolves incredibly fast for two reasons. 1) It's high population within a human, numbering far into the trillions per individual.  2) It's use of a error prone reverse transcriptase to copy its genes.  This essentially is the perfect storm of drug resistance evolution.  That being the case, the current strategy is to overwhelm the HIV virus making it necessary for it to evolve multiple adaptations at the same time--a feat that is difficult but not impossible and the drugs only currently delay the process of evolution.

http://www.bio.utexas.edu/faculty/sjasper/bio212/histevolth.html
Also:
http://scholar.harvard.edu/pennings/pages/hiv-drug-resistance

  Great lists of observed evolution events: http://www.wired.com/wiredscience/2008/12/evolutionexampl/ http://listverse.com/2011/11/19/8-examples-of-evolution-in-action/ http://phylointelligence.com/observed.html Artificial selection Dogs

http://www.macwebguru.com/2010/09/11/the-dog/

http://annwyn.info/wolf/wolf23.html

Wild mustard

http://evolution.berkeley.edu/evosite/evo101/IIIE4Evochange.shtml

Corn

http://faculty.uca.edu/johnc/introdarwin.htm

  Biogeography: Because migration can be difficult and take time, biogeography can spatial represent evolutionary change over time.  This phenomena is most obvious in 'ring species' that start spreading slowly over many generations around geographic obstacles, like mountain ranges. The population diverges into two as it spreads around the geographic obstacle and by the time the species meets again on the other side of the obstacle so much time, mutation, genetic drift, and selection has taken place that the two species can no longer interbreed.  Even more interesting is that the two separate species can interbreed with those geographically closest to them from the direction that they migrated. Ensatina salamander of California - The species spread from the north and traveled around the Central Valley and diverged into species that can not mate with each other in the south, due to their divergence, but can mate with the species in the direction that they migrated from.

http://evolution.berkeley.edu/evolibrary/article/0_0_0/devitt_02

 The Greenish Warbler (Phylloscopus nitidus) historically spread around the Himalayas and can interbreed with those from the direction they spread but not those that long ago diverged from them and spread around the opposite side of the mountain range.

http://mappingignorance.org/2013/06/13/speciation-beyond-sexuality-critiques-to-the-biological-species-concept/ Updated genetics: http://www.sciencedaily.com/releases/2014/05/140525154742.htm

The Larus Gulls of the Northern Hemisphere: Notice the darkening of the feathers in a clockwise direction starting at the bottom.  Gull species near each other can interbreed, except between the Herring Gull and the Lesser Black-Backed Gull that diverged from each other long the longest ago.  This inability to breed tells the story of how the species likely spread overtime around the world and met back up, now no longer able to interbreed.

 

http://darwiniana.org/zimmergulls.htm

 

When species are in a particular location for a long time, genetic diversity tends to go up as new mutations are added to the population. When species migrate into new territories, genetic diversity tends to be low because those new areas are populated by a few individuals. One way of reading this diagram is a time scale. The more genetic diversity in an area, the longer humans have lived there. Darwin knew this and speculated that humans originated in Africa, since most great apes are native there.http://whyevolutionistrue.wordpress.com/2011/04/16/where-on-earth-did-language-begin/

Fonte: http://www.evolutionevidence.org/evidence/progressions/