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Every so often, something incredibly beautiful and delicate comes out of the fossil record. It can be the microscopic fossil of extinct plankton or the near-complete skeleton of a massive dinosaur. Then there are those fossils which show a surprising degree of completeness, presenting real snapshots of a long-lost age. They are the top 10 finest amber fossils ever.

We have had a long relationship with amber, the beautiful petrified tree resin. Amber is mostly orange, reddish or gold in color while sometimes there might even be red or the rare green and blue amber. We use it mostly for jewelry but amber also became important to paleontologists in understanding the ancient world. Once a viscous liquid, it becomes solid upon fossilization, often trapping whatever creatures or other small organisms that originally get stuck in the substance.

Sometimes more surprising things have gotten caught in amber. Collectors and scientists have found not just bugs entombed in tree resin, but even animals as large as lizards, frogs and salamanders can be preserved in impressive detail. Skin, scales, fur and feathers are just some of the incredibly detailed features found in amber. Insects may be caught having sex. Even the reproductive organs of plants cannot escape the sticky clutches of fresh resin.

One thing amber does not preserve however, is DNA. So unfortunately, a Jurassic Park-like scenario will be impossible to create. Nevertheless we have changed our views of the evolution of many smaller beasts thanks to amber’s remarkable ability to preserve. There are so many amazing discoveries to choose from, with fossils ranging from more than 230 to 20 million years old. We at Earth Archives are bringing you our top 10 most incredible amber fossils.

10

Flea with plague bacterium

Image credit: Dr. George Poinar Jr.
Location: Dominican Republic
Age: 20 million years old

We often remember the plague bacterium as the killer that wiped out much of Europe during the Middle Ages. Yet the origins of the plague bacterium date back to before humankind even evolved. One of the world’s foremost amber researchers, Dr. George Poinar Jr. and colleagues from the Oregon State University described a suspicious-looking flea from Dominican amber that was about 20 million years old. Dominican amber is one of the most important kinds of amber there is, often being nearly transparent and coming from the resin of the extinct tree Hymenaea protera. Most Dominican amber preserves remains of neotropical forests that existed in the region between 25 and 20 million years ago. It is mostly found in shades of yellow, although reds and even blues are often mined in this area.

Numerous insects have already been found encased in these ambers so it was not too much of a surprise to find a flea in amber. What came next was the shocker, the discovery of what appeared to be the deadly plague germ in the creature’s body. For a long time it was thought that the plague bug became its current self much more recently. Poinar argued that the germ may or may not be an ancestral form of the plague bacterium or Yersinia pestis. He went on to state that several strains of the disease had evolved and gone extinct over time, so advanced as the new find was, its actual identity was a bit of a mystery at the time.

He did mention however, that the microbe was present in a dried droplet of blood in the flea’s proboscis or sucking mouthparts. This suggested that the germ was being transmitted the same way that modern rat fleas transmit the plague bug, through drinking the blood of their victims. The age of the find puts it around the Early Miocene Epoch, right when mammalian diversity was beginning to explode. At the time, the Dominican Republic was possibly covered by thick tropical forests and the flea had been unlucky enough to get trapped in some freshly flowing resin. Poinar published his findings in 2015, in the Journal of Medical Epidemiology.

Earliest insect parental care

Image credit: Dr. Bo Wang
Location: Myanmar
Age: 100 million years old 

 

 

The earliest example of a motherly insect was discovered in Burmese amber dating back to the Early Cretaceous. Burmese amber, also known as burmite, is found mostly in the Hukawng Valley region of Kachin State, Myanmar. Much of it is approximately the same age, roughly 100 million years old, thus making it the oldest gem-quality amber in the world. This puts burmite as a dinosaur-age amber although we still have no traces of the country’s bigger extinct inhabitants. The mother insect find was published and scientifically described by Chinese paleontologist Dr. Bo Wang, a fellow at the Alexander von Humboldt Foundation, and a team of colleagues from Poland, the UK and China. Dr. Wang has said that 100-million-year-old care of offspring was unknown among insects until now. The find was published in the journal eLIFE. The bug is question is a new genus, named Wathondara kotejai, after a Buddhist goddess. The species name of W. kotejai, meanwhile, comes from late Polish entomologist Jan Koteja.


The bug was an ensign scale insect, a member of a herbivorous species that is still alive today and lives by sucking plant juices. Even today, scale insects look and act in very much the same way. The female Wathondara was wingless, just like modern female scale insects. Attached to her body were 60 eggs, while a waxy cover protected both her and her precious brood from conditions of wet and dry. Even her newly hatched babies, her nymphs, can be seen stuck to her in the amber. It is not often that animals with their brood are found in such incredibly well preserved state, which makes Wathondara a precious rarity in the fossil record.

8

Spider attacking a wasp (acima)

Image credit: Dr. George Poinar Jr.
Location: Myanmar
Age: 100 million years old 

 

Predation among terrestrial arthropods is one other incredible act that is often trapped and preserved in amber, with this example being that of a spider and its victim. The prey insect was a hapless male parasitic wasp that had flown into an orb weaver spider’s web. Even fifteen strands of silk had been found with the dueling minibeasts. Another spider from the same block shows us what might be the first remains of social behavior among spiders. The fossil was found in the Hukawng Valley and described scientifically by amber expert and entomologist Dr. George Poinar Jr.

He and Kentucky-based collector Ron Buckley published their find in the scientific journal Historical Biology in October 2012. Poinar also stated that while there have been finds of spiders and their prey caught in resin, there has never been an actual predator-prey interaction between the two. In this new specimen, the wasp was being actively attacked by the spider, as can be seen in the amber block. So in life, the unfortunate wasp was probably already in the spider’s clutches when the sticky resin flowed over them, entrapping them for 100 million years. According the the scientific team, the wasp belonged to a parasitic genus that is still in existence today. It is a Cascoscelio incassus, a member of a family of wasps that often parasitizes the eggs and young of spiders while the bristly orb-weaver is a species called Geratonephila burmanica.

Ant with parasitic mite (abaixo)

Image credit: Dr. Jason Dunlop
Location: Baltic region of Russia (precise location unknown). Received from the Naturmuseum Senckenberg in Frankfurt
Age: Between 49 and 44 million years old

 

Even insects can have parasites, and one of the deadliest insect parasites is a kind of mite called Varroa that attacks bee and wasp species. These tiny, somewhat furry mites have rounded bodies and run around at incredible speeds as they try to find hosts. These creatures are potent and powerful enough to bring down an entire colony of bees at times, spreading through the hive at an incredible speed. An ancient equivalent has also been discovered, one with habits similar to the Varroa mite, but instead of calmly sitting atop its host, this mite was caught in mid-attack. It was just 0.7 millimeters long, which is about as big as these little creatures get.

The describer of the amber fossil is Dr. Jason Dunlop, an arachnologist at the Leibniz Institute for Evolution and Biodiversity Science in Berlin. He added that the mite was a member of the incredibly widespread Myrmozercon, a genus which is actually quite common even today. Its intended victim was an ant, identified as a Ctenobethylus goepperti by the team. The two animals were found in a block of Baltic amber from Saxony in East Germany, and parts of Russia. This form of amber is called succinite, and often comes from pine resin. The Baltic is home to the most extensive of all amber deposits, and most date back to the Eocene, the same time as the parasitic mite and ant.

Erect harvestman (abaixo)

Image credit: Dr. Jason Dunlop
Location: Myanmar
Age: 99 million years old

 


A relative of spiders, a harvestman or daddy longlegs seems to have had another long appendage, this time not a leg through probably just as mobile when used correctly. Another of Dr. Dunlop’s findings, this harvestman, only a few months into puberty, had been swamped by resin in the Cretaceous forests of Hukawng in Myanmar.

This new and somewhat prodigious finding was published in the journal The Science of Nature by Dunlop and his team. The little male arachnid was a genus named Halitherses grimaldii and its massively elongated penis with a heart-shaped tip is normal for most harvestmen. The genitalia of harvestmen are somewhat different from those of spiders, which often have jaw-based genitals in their pedipalps. Dunlop believes that the daddy longlegs had a post-mortem erection, with blood flowing into its elongated penis just as it died and was covered in resin.

First salamander in amber (abaixo)

Image credit: Dr. George Poinar Jr.
Location: Dominican Republic
Age: 20 million years old

Salamanders are absent from the Caribbean islands today. But one block of amber from this area preserves a salamander nonetheless. Not only that, but it had just gone through a rough spot in its life before succumbing to the viscous resin. One of its legs had been bitten off by an attacking predator before falling into a resin deposit, entombing it forever since the Early Miocene.

Poinar and team, who studied the fossil, said that the salamander was an extinct Palaeoplethodon hispaniolae, a close relative of the numerous salamanders of today’s Appalachians. Even the tree from which the amber came from, is more closely related to East African trees rather than anything in the Caribbean. Thus the find may hold clues to how life on these islands evolved, with the current theory being that these little amphibians rafted onto the islands on floating logs and other forms of vegetation. All these Caribbean salamanders may have gone extinct due to climatic change, says Poinar yet again, having published the find in the journal Paleodiversity.

Plant sex (abaixo)

Image credit: Dr. George Poinar Jr.
Location: Myanmar
Age: 99 million years old

 One of the strangest things ever to be entombed in resin is the act of sex between two flowering plants that actually date back to the earliest days of flowers in general. The diminutive flowers of the Cretaceous Micropetasos burmensis were discovered in a block from Hukawng Valley. Poinar published the study in the December issue of the Journal of the Botanical Research Institute in Texas. He explains that the two plants are doing something very similar to modern flowers, with the anther or male part being inserted into the female part or the stigma. While both the male pollen tubes and female stigma have been found in amber previously, never has sex between plants been discovered, making this one a first in fossils.

First chameleon and gecko ancestors

Image credit: Edward Leo Stanley
Location: Myanmar
Age: 100 million years old

 

 

 Burmese amber continues to surprise us, now with the incredible find of numerous well-preserved lizards stuck in tree resin. There was not just one lizard found in the amber, not two or three but twelve of them in total. The specimens were all collected many years ago from a Hukawng amber mine but only now are the best specimens undergoing study. The finds were described in the scientific journal Science Advances, by Edward Stanley, a University of Florida postdoctoral student in herpetology at the Florida Museum of Natural History. Micro CT-scans of the dime-sized reptiles showed him that he was looking at some of the first geckos and chameleons ever to exist. The state in which they were preserved allowed for the presence of toe pads, teeth, claws and even the scales. Stanley’s team created impressive CT-scanned computer models of the lizards and this allowed them to study the specimens in further detail. Analysis of the gecko for example, revealed that it had the sticky pads for climbing and gripping, just as its modern descendants do today.

Oldest arthropods ever to be preserved in amber

Image credit: Alexander Schmidt, Eugenio Ragazzi and Guido Roghi
Location: Italy
Age: 230 million years old

 The Dolomite Alps of northeastern Italy have revealed plenty of droplets of amber, each between two and six millimeters in length and not that remarkable-looking on the outside. Yet an international team of researchers led by Eugenio Ragazzi and Guido Roghi from the University of Padova and by Alexander Schmidt from the University of Göttingen discovered some of the oldest ever arthropods to be caught in tree resin. There are two genera in the droplets, both gall mites. This in itself is surprising. Gall mites today predominantly feed on flowering plants. Yet these ancient mites date back to the Triassic, to before flowers had evolved. Source: Schmidt A.R. et al., Arthropods in amber from the Triassic Period. Proc Natl Acad Sci U S A. 2012 Sep 11; 109(37):14796-801. doi: 10.1073/pnas.1208464109

 


 The researchers classified the two newly known genera as Triasacarus fedelei and Ampezzoa triassica. According both to them and to known amber researcher Dr. David Grimaldi, the finding of two highly advanced and recognizable gall mites so early in time surprised them. The scientists were expecting something much more primitive instead, perhaps a transitional form and not something so developed.

Dinosaur and bird feathers in amber

Image credit: Ryan C. McKellar
Location: Canada
Age: Between 80 and 75 million years old

 

 

 

 The discovery of feathers encased in fossilized resin was one of the most prodigious finds of the last decade. Altogether, 11 specimens were discovered in a Canadian deposit dating back to the Late Cretaceous, the twilight years of the dinosaurs. With a new dinosaur revolution in full swing, the image of the birdlike and active dinosaur has become unavoidable. Feathers have been preserved in the silty and volcanic ash-filled lake sediments of China and reveal not only the evolutionary secrets of birds but also those of other non-bird dinosaurs.

 

 The discovery was published in the journal Science in the year 2011, with Ryan McKellar of the University of Alberta leading the study. Even though the specimens were too delicate and precious to be broken into, advanced microscopy allowed the scientists to look into the blocks of amber to reveal impressive branched structures inside. Most of them seem to have been simple, fur-like insulatory structures while others had a hardened rachis in the middle and resembled flight feathers. They resembled other preserved feathers to a tee, but with an additional surprise to add to the mix. They revealed the color of the actual feathers, with shades of black and brown being preserved. McKellar points out that this is no Jurassic Park scenario, for no traces of DNA exist in the remains.
 

Dóceis e agressivas: seleção em grupo?

Experimento com aranhas sociais alega ter demonstrado, pela primeira vez em ambiente selvagem, teoria polêmica de que a seleção natural pode levar à adaptação da colônia. Darwin dizia que ela agiria apenas no indivíduo. 

 

Por: Cássio Leite Vieira

Publicado em 01/12/2014 | Atualizado em 01/12/2014

Presentes da América do Norte à do Sul, as ‘A. studiosus’ comem, em geral, insetos, mas até restos de ratos e pássaros já foram encontrados nas teias, que chegam a ter o tamanho de um carro. (foto: Universidade de Pittsburgh/ cortesia Judith Gallagher) 

 

Experimento que deslocou e alterou a composição de colônias de aranhas alega ter demonstrado – pela primeira vez em ambiente selvagem – algo que é tópico polêmico entre biólogos desde o século 19. A equipe de Jonathan Pruitt, da Universidade de Pittsburgh, e Charles Goodnight, da Universidade de Vermont, ambas nos Estados Unidos, montaram, em seis locais diferentes, 53 colônias da aranha Anelosimus studiosus, espécie diminuta (até 1 cm), de cor alaranjada, mais conhecida por ter fêmeas dóceis e agressivas.

Na natureza, a razão dóceis/agressivas é tal que maximiza as chances de sobrevivência da colônia

Na natureza, a razão dóceis/agressivas é tal que maximiza as chances de sobrevivência da colônia. Cada um desses dois temperamentos tem um papel na comunidade. A dupla de pesquisadores acompanhou também 20 colônias que nem foram perturbadas, nem deslocadas, servindo, assim, como grupo-controle.
As A. studiosus comem, em geral, insetos, mas até restos de ratos e pássaros já foram encontrados nas teias, que podem chegar a ter o tamanho de um carro. Essa espécie espalha-se da América do Norte à do Sul.

Risco de extinção 

Parte das 53 colônias ‘artificiais’ foi levada para locais bem diferentes daqueles em que elas haviam se formado. Outra parte teve a razão dóceis/agressivas original alterada. Segundo Pruitt, essas perturbações são vistas pelas colônias como possível risco de extinção.
Quando não perturbadas, essa razão responde a fatores internos e externos. Se a colônia se forma num ambiente de muita comida, a tendência é que seja dominada por dóceis, pois não há tanta necessidade de caçar. À medida que a colônia cresce, a principal ameaça à sobrevivência em longo prazo são os parasitas sociais, que roubam a comida. Nesses casos, a tendência é que aumente o número de agressivas, que os combatem e protegem a colônia.
Se a colônia começa a se formar num local de poucos recursos, a tendência é que ela seja dominada por agressivas (caçadoras). Mas aí a maior ameaça é o canibalismo de ovos, praticado pelas agressivas. Então, à medida que a colônia cresce, aumentam as dóceis. Cada colônia ajusta a razão dóceis/agressivas para o ambiente em que está.

Volta às origens 

Depois de duas gerações, Pruitt e Goodnight notaram que as colônias – sem se importar com o novo ambiente – tendiam a voltar à razão dóceis/agressivas original, ou seja, aquela que maximizava as chances de elas sobreviverem no hábitat em que haviam se formado. Segundo os autores, as aranhas parecem não ter ideia de que estão num novo ambiente. E esse retorno à razão original pode até levar a colônia à extinção.

O estudo com ‘A. studiosus’ mostra a seleção natural agindo em uma característica coletiva que é passada de geração a geração e é determinante para a sobrevivência (ou não) da colônia. (foto: Universidade de Pittsburgh/ cortesia Judith Gallagher)

Para Pruitt e Goodnight, essa alteração mostra a seleção natural agindo em uma característica coletiva (razão dóceis/agressivas) que é passada de geração a geração e é determinante para a sobrevivência (ou não) da colônia. “Nosso estudo mostra a seleção de grupo atuando num ambiente natural – e sobre uma característica [razão] que é herdada – e que levou à adaptação em nível de colônia [grupo]”, diz Pruitt.
No artigo, os autores dizem por que esses resultados são importantes: “pesquisadores renomados têm defendido que a seleção em grupo não pode levar à adaptação do grupo [exceto em condições controladas] e que a teoria da seleção em grupo é ineficiente e falida”.

Indivíduo ou grupo? 

Pelo tom, dá para perceber que seleção em grupo é assunto polêmico na biologia. Razão simplificada: a leitura mais comum da teoria proposta pelo naturalista inglês Charles Darwin (1809-1882) é que a seleção natural ocorre apenas em nível de indivíduo. Mas, na chamada teoria da seleção em grupo, membros de espécies sociais exibiriam características individuais de comportamento que dariam maior ou menor chance de sobrevivência ao grupo. Ou seja, a seleção natural operaria em nível de grupo e produziria adaptações nesse nível.

Na chamada teoria da seleção em grupo, membros de espécies sociais exibiriam características individuais de comportamento que dariam maior ou menor chance de sobrevivência ao grupo

Essa discussão começou com o próprio Darwin, mas ganhou fôlego a partir da década de 1960.
Mas, se a seleção natural age apenas sobre o indivíduo, como explicar, por exemplo, a cooperação de insetos sociais, como é o caso de abelhas, formigas – e, no caso, das A. studiosus. Afinal, se o que importa é o ‘eu’, por que aumentar as chances de outro indivíduo sobreviver e passar seus genes para frente, na forma de descendentes férteis? Esse já foi assunto de reportagem aqui. 

Parte da explicação para a cooperação é que animais sociais são aparentados – então, ajudar o outro significa, de algum modo, ajudar a si mesmo. Pruitt e Goodnight dizem ter revelado um mecanismo complementar ao parentesco.

A polêmica sobre se a seleção em grupo é ou não válida vai continuar. Há aqueles, como o psicólogo norte-americano Steven Pinker, que nem mesmo podem ouvir a expressão. E há, agora, os resultados de Pruitt e Goodnight.
É esperar para ver. Por enquanto, há dúvidas. Mas, ao final, haverá uma certeza: ganha a biologia.

Três perguntas para Pruitt

Como diferenciar fêmeas dóceis das agressivas?Com base no espaço que demandam. As dóceis se mantêm agrupadas; as agressivas, distantes entre si.

Qual o papel de cada uma delas na colônia?As agressivas capturam individualmente presas, defendem a colônia e reparam a teia. As dóceis cuidam da prole.

Os senhores pretendem continuar esses experimentos com aranhas sociais? Se sim, para quê? Pretendemos fazer um ou dois novos experimentos. Primeiramente, gostaríamos de saber como as aranhas manipulam a composição [razão dóceis/agressivas] de seus grupos. Estariam se livrando de fenótipos (dóceis/agressivas) que estão em excesso? Ou será que as que estão em excesso abandonam a colônia ou se tornam ajudantes [qualquer dócil ou agressiva que deixa de se reproduzir para ajudar outros membros da colônia]?
Não temos ainda essas respostas. Gostaríamos de poder manipular a quantidade de predadores, o número de parasitas sociais [que roubam comida da colônia] e a frequência de surtos de doenças, para testar que fatores são responsáveis pela seleção de grupo específica de cada ambiente natural. Seria resultado de apenas um fator? Ou seriam vários fatores combinados que gerariam as composições ideais?

New Findings: How Do Scorpions Make Their Tails?

A new study led by scientists at the American Museum of Natural History reveals the genetic blueprint behind the patterning of scorpion tails. Scientists have long been puzzled by the development of scorpion tails—which in addition to venom-producing glands also have light-sensing capabilities—because there weren't enough known genes to code for their many segments.

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But the new research, which was published today in Proceedings of The Royal Society B, reveals that scorpions have more "body-planning" genes than previously thought, potentially solving the scorpion tail mystery.

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"Scorpions have six segment-types in the back-end of their body, almost double the number seen in their closest relatives. They also are the only arthropods to have a group of segments exclusively dedicated to prey capture and defense," says Prashant Sharma, a postdoctoral researcher in the Museum'sDivision of Invertebrate Zoology and lead author of the paper. "The question is how to pattern this kind of complexity."

Along with Ward Wheeler, a curator in the Museum's Division of Invertebrate Zoology, and colleagues at Harvard University, Sharma focused on a group of genes known as the Hox family, which encode the body plan in numerous organisms from worms to humans. By acting in different combinations, these genes control whether a given portion of the embryo will develop mouthparts, wings, or gills, for example.

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Hox genes are expressed, from head to tail, in the same order as they appear in the genetic code. The system works by "staggering" the expression of the gene family. The first gene in the Hox family will be expressed starting in the head. Subsequent genes, however, begin to be expressed one section of the embryo at a time, causing each section to have a unique genetic cocktail: If , say, a given section has genes X and Y, for example, it may produce legs, while if it had genes X, Y, and Z, it would make lungs. The staggering of these Hox genes allows many different segment types to develop. Manipulation of a single Hox gene can turn what would be a fly's antenna into a leg, or even be used to create a 10-legged spider.

Arachnids—the group of arthropods that includes scorpions, spiders, and daddy-long-legs—are presumed to have 10 Hox genes. In non-scorpion arthropods, six of the 10 Hox genes have been shown to aid in the patterning of the front part of the organism that includes the legs and feeding appendages. This leaves only four to control the back end. Four genes, however, are not enough to pattern the scorpion's tail.

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"If the previous model were true, we couldn't actually make a scorpion," Sharma said. "We would need either more genes or a different model."

The researchers used the Arizona bark scorpion to investigate Hox gene makeup. By taking tissue samples of scorpion embryos and determining the genes that were being expressed at a given developmental stage, they discovered that 19 different Hox genes are active during development, instead of the typical 10.

"But just because scorpions have a lot of genes, it doesn't mean those genes have anything to do with body patterning," Sharma said. 

The group began the process of testing whether the genes are all actually involved in shaping the scorpion's tail. First, the researchers bathed embryonic tissue samples with probes that change color if a certain gene was being expressed. Their results uphold the model: the appearance of each gene in the family is staggered and coincides with a shift in segment identity. While further mutative experiments would be required to definitively prove the connection between genetic code and body form, it seems that the scorpion's extra genes do in fact pattern its tail.