«The new outcrops of amber in Australasia will allow us to better complete the ancient puzzle of life»

Scoop interview with the scientific team (https://doi.org/10.1038/s41598-020-62252-z)

Photo A- Ant
Figure A: One of the new worker ants discovered (head is on the top of the image, evidenced by one antenna) in Anglesea amber ca. 41 Ma old. Body length is 1.4 mm (credit: IGME).

During these days marked by the quarantine, news from science has caught the attention of readers, because it showed us two insects captured in Anglease amber while mating ca. 41 millions of years ago, in a remote region of the current Australia.

Behind the anecdote are years of work and many more interesting discoveries in Australian amber by an international, multidisciplinary team including Spanish and Australian researchers, with Jeffrey Stilwell from Monash University, Australia, Enrique Peñalver from the Geological Survey of Spain (IGME), and Antonio Arillo, from the Complutense University. But, above all, it is a first look at the ecosystem from about 41 million years ago. To understand how amber becomes the best ally of scientists, we asked the experts in this interview.

How did you start discovering amber in this region and what was the most exciting find?

Jeffrey Stilwell: In May 2011 I and two Monash University palaeontology students were researching Cretaceous-aged cores in the Otway Basin, southern Victoria, with the Origin Energy Company (searching for gas deposits), when I noticed abundant, in situ amber with bioinclusions—the first ever discovered in Australia. I then applied to the Australian Research Council to study this amber and also explore for more amber-bearing deposits. In a short period of time, my team and I discovered the oldest and first ever animals and plants in S Gondwana, and the oldest ever recorded amber from S Pangea—exciting new data for amber palaeontology.

Enrique, What is in your opinion the main discovery in your new paper, and why is it important?

Enrique Peñalver: The main discovery is the potential of Australasia to provide exceptionally preserved fossils of diverse arthropods and plant remains in a wide spectrum of geologic times. We must consider that Australia was an important part of the southern ancient continent named Gondwana, and the evolution of the organisms there occurred during a lot of millions of years in isolated conditions. With the discovery of more amber-bearing outcrops and the excavation and preparation of more amber samples, we will be able to know in detail the evolutionary history of diverse forest organisms and better complete the ancient puzzle of the life.

Enrique, how relevant is the Australian amber you and your colleagues discovered in terms of our understanding of the ancient forest ecosystems in the southern high latitudes?

Enrique Peñalver: Amber exceptionally preserves up to very tiny arthropods, a millimeter or less in size, like mites, thus our comprehension of the biodiversity and ecology of ancient forest ecosystems can be rich in details, and varied in types of information because this material also provides rare evidence of paleobehavior, as is mating pairs of insects. Much work must be done to discover fossils in Triassic and Cretaceous Australian amber, in order to know these more interesting periods in the evolution of the forest ecosystems.

thumbnail_Photo B - three flies
Figure B: three nematoceran flies (“mosquitos”; family Ceratopogonidae), males and females, trapped in the same resin flow also from Anglesea amber. Body lengths are ca. 1 mm (credit: IGME).

How relevant is the newly discovered Triassic amber in Australasia?

Jeffrey Stilwell: The major find of Triassic amber in Australia provides tantalizing new evidence of Pangean-wide resin-producing trees with sites in the Dolomites (N Italy), once part of N Pangea, and Tasmania in Australia, once part of S Pangea. What this means is that it is undoubtedly no coincidence that both Pangean sites are the same age through associated palynomorphs and corresponds to a time of changing climate in the Late Triassic (Carnian Stage) ~230 Ma, known as the Carnian Pluvial Episode/Event. This is an exciting new development for inferring palaeoclimate signals in the early Mesozoic Era and also the associated new record of Triassic Southern Hemisphere amber with the potential of more future finds in all coal deposits of Australia and New Zealand. It is important to note that one important Triassic amber site was found in Alicante Province (SE Spain), but this amber is currently under study by the IGME and the Museo Paleontológico de Elche.

«This is an exciting new development for inferring palaeoclimate signals in the early Mesozoic Era and also the associated new record of Triassic Southern Hemisphere amber with the potential of more future finds in all coal deposits of Australia and New Zealand»

What other types of features of the forest paleoecosystem can be studied thanks to the amber record of this region?

Antonio Arillo: Amber provides a lot of information about the amber-bearing forest, not only tiny animals are fossilized but also many plant remains, including pollen grains and spores. This helps to reconstruct the paleoenvironment and it lets us hypothesize about trophic relationships.

Is it surprising that you and your colleagues discovered arthropods and other bioinclusions in Australian amber? 

Enrique Peñalver: Historically, this region was considered virtually devoid of amber. Our research shows that it is actually abundant, but most interesting is that it occurred in a geologic time interval that is unexpectedly broad and that it can contain abundant bioinclusions.

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Jeffrey, apart of the southeast Australia, What other regions in your country do you think are potentially rich in amber? Are you planning to explore them?

Jeffrey Stilwell: As we now know of abundant fossiliferous amber in both Tasmania and Victoria, we will also commence in the near future comparable coal and other sedimentary deposits in Queensland. Although there was an earlier report of amber from the Cape York Peninsula in far northern Queensland, none of this amber is in situ, and as such is found nearly all as ‘float’ and also quite poorly dated in terms of biostratigraphy. There are potential other parts of Queensland to explore of Mesozoic and early Cenozoic age. Time will tell! Even if we do not discover any more amber elsewhere, the sites already recorded in Victoria and Tasmania will yield enough amber for many decades of study to come!

Enrique, how can the amber preserved «frozen behavior», and why the position the animals are in is not taphonomic, or may be hazardous?

Enrique Peñalver: Fresh resin acts as a trap for insects that touch it and rapidly embedded them. Commonly the agony is short and insects can be preserved evidencing their behavior, like it occurred in Pompeii with their citizens in 79 AD. The two flies captured in Australian amber while mating show the typical end-to-end position and genital appendages in contact.

Antonio, apart from the «frozen behavior» of two flies preserved while mating, this type of exceptional “frozen” records, What other important data do they provide us?

Antonio Arillo: Amber provides a wide range of these frozen behaviors, which are expected to be found in Australian amber. Not only mating individuals but both intraspecific relations (as egg-lying, mate guarding, swarms) and interspecific relations (predation, parasitism, phoresy, symbiosis). Mating individuals are very interesting as we can define a new species in exceptional detail, because exceptionally we can describe its sexual dimorphism… I mean, not only the anatomical features of the male or the female but both sexes. This circumstance is not always possible studding living organisms, because sometimes we only found one specimen or a few specimens of the same sex in the modern ecosystems. To know with complete confidence that fossils of two different morphologies correspond to the same species (male-female) is extremely uncommon, but without doubt in the case of mating specimens as the Australian specimens in amber.

«Amber provides a wide range of these frozen behaviors, which are expected to be found in Australian amber. Not only mating individuals but both intraspecific relations (as egg-lying, mate guarding, swarms) and interspecific relations (predation, parasitism, phoresy, symbiosis)»

Antonio, as an expert in fossil and living mites, How do you value that you can know the mite fauna exceptionally preserved in Anglesea and Strahan ambers millions of years old?

Antonio Arillo: Mites are rarely preserved as compression fossils due to their minute size. So amber is an exceptional source (almost the only one) of information to understand their anatomy, their ancient distributions and the evolution of the different groups.

Jeffrey, how would you describe your visit to the Geological Survey of Spain in October 2016 at the beginning of the study of these arthropods in amber? We know that you also visited other research institutions in search of multidisciplinary collaboration in order to lead a whole study of these new ambers.

Jeffrey Stilwell:I am so pleased that I contacted Enrique in order to work out viable strategies and collaboration to study the fossiliferous amber deposits of Australia, as this is an entirely new project for this country. When I visited the Institute in 2016, Enrique and I made some fantastic discoveries, and over the month, we learned just how important the Paleogene ambers of Australia are in a global sense. It became readily apparent in 2016 that many modern elements of the Australian terrestrial biota have been captured in amber, dating from ~54-40 Ma, indicating the great antiquity of the modern ecosystems, which is very significant for many reasons. Further, Australia has never been a major player in amber palaeontology until now. The discoveries keep coming, and there is no sign of abating, which is extraordinary. As we are now extracting quite big pieces of Paleogene amber from the coal with scores of new animals and plants, we are expecting many more biotic surprises! We have just started to scratch the surface in our knowledge of these subpolar greenhouse Earth ecosystems.

thumbnail_Reconstrucción ácaro ámbar New Zealand-Marchantiopsida
Reconstruction of the mite found in amber of Strahan (western Tasmania), of the early Eocene. Coloration is tentative.

Antonio, regarding to the experience of the Spanish team that studies Spanish amber under a project of the Ministry of Science and Innovation, How extent can it serve to study amber so varied in age and from a region so far from our country?

Antonio Arillo: Well, at a first sight you could think Australia is too remote to made comparison with Spanish and other European ambers. But this is wrong, we find many coincidences between Spanish and Myanmar Cretaceous amber faunas (that are almost cotemporaneous) and probably Anglesea amber will show this type of similitude with contemporaneous European ambers (Baltic, Oise, Bitterfeld, Rovno, etc.)

Jeffrey, what are the plans to continue this relevant research and what are your expectative?

Jeffrey Stilwell: As highlighted above, we are just getting started with the research! We are currently planning several specialist papers, now that the first synthesis paper has been published. The success of this paper is reflected in the major global press on our finds, including rare frozen behaviors such as mating flies. In the last few months, the number of bioinclusions in the amber has climbed substantially, meaning that there is a huge amount of exciting science to complete, which will keep adding pieces to the ancient puzzle of terrestrial ecosystems of Australia and New Zealand, previously virtually unknown.

Enrique, has your research of the Austrasian amber, and the rest of your studies, been impacted by the COVID-19 outbreak?

Enrique Peñalver: The IGME, the Complutense University and the Monash University are temporally closed, but all the coauthors of our new paper are working at home, fortunately. We have a lot of data from the Australian amber and we are preparing at home more detailed articles on these new animals and plants as Jeff has explained. We are convinced that globally all the citizens we must continue with our work to the extent possible, as the best manner to fight the impact of the COVID-19, not only the more relevant people now as virologists, biotechnologists, epidemiologists, sanitarians, law enforcement, supply chain workers, etc.

You can check the impact on media at Flipboard

Overview of attention for article published in Scientific Reports, April 2020

Y si quieres leer esta noticia en español accede a “Los nuevos yacimientos de ámbar de Australasia nos permitirán completar mejor el antiguo rompecabezas de la vida”

Last E. Peñalver’s papers

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