PALEONTOLOGY
Ancient polar sea reptile fossil is oldest ever found in Southern Hemisphere
IMAGE:
Reconstruction of the oldest sea-going reptile from the Southern Hemisphere. Nothosaurs swimming along the ancient southern polar coast of what is now New ZEALAND AROUND 246 MILLION YEARS AGO. ARTWORK BY STAVROS KUNDROMICHALIS.
view moreCREDIT: STAVROS KUNDROMICHALIS
An international team of scientists has identified the oldest fossil of a sea-going reptile from the Southern Hemisphere – a nothosaur vertebra found on New Zealand’s South Island. 246 million years ago, at the beginning of the Age of Dinosaurs, New Zealand was located on the southern polar coast of a vast super-ocean called Panthalassa.
Reptiles first invaded the seas after a catastrophic mass extinction that devastated marine ecosystems and paved the way for the dawn of the Age of Dinosaurs almost 252 million years ago. Evidence for this evolutionary milestone has only been discovered in a few places around the world: on the Arctic island of Spitsbergen, northwestern North America and southwestern China. Although represented by just a single vertebra that was excavated from a boulder in a stream bed at the foot of Mount Harper on the South Island of New Zealand – this discovery has shed new light on the previously unknown record of early sea reptiles from the Southern Hemisphere.
Reptiles ruled the seas for millions of years before dinosaurs dominated the land. The most diverse and geologically longest surviving group were the sauropterygians, with an evolutionary history spanning over 180 million years. The group included the long-necked plesiosaurs, which resembled the popular image of the Loch Ness Monster. Nothosaurs were distant predecessors of the Plesiosaurs. They could grow up to seven metres long and swam using four paddle-like limbs. Nothosaurs had flattened skulls with a meshwork of slender conical teeth that were used to catch fish and squid.
The New Zealand nothosaur was discovered during a geological survey in 1978, but its importance was not fully recognised until palaeontologists from Sweden, Norway, New Zealand, Australia and East Timor joined their expertise to examine and analyse the vertebra and other associated fossils.
“The nothosaur found in New Zealand is over 40 million years older than the previously oldest known sauropterygian fossils from the Southern Hemisphere. We show that these ancient sea reptiles lived in a shallow coastal environment teeming with marine creatures within what was then the southern polar circle,” explains Dr Benjamin Kear from The Museum of Evolution at Uppsala University, lead author on the study.
The oldest nothosaur fossils are around 248 million years old and have been found along an ancient northern low-latitude belt that stretched from the remote northeastern to northwestern margins of the Panthalassa super-ocean. The origin, distribution and timing of when nothosaurs reached these distant areas are still debated. Some theories suggest that they either migrated along northern polar coastlines, or swam through inland seaways, or used currents to cross the Panthalassa super-ocean.
The new nothosaur fossil from New Zealand has now upended these long-standing hypotheses.
“Using a time-calibrated evolutionary model of sauropterygian global distributions, we show that nothosaurs originated near the equator, then rapidly spread both northwards and southwards at the same time as complex marine ecosystems became re-established after the cataclysmic mass extinction that marked the beginning of the Age of Dinosaurs” says Kear.
“The beginning of the Age of Dinosaurs was characterised by extreme global warming, which allowed these marine reptiles to thrive at the South Pole. This also suggests that the ancient polar regions were a likely route for their earliest global migrations, much like the epic trans-oceanic journeys undertaken by whales today. Undoubtedly, there are more fossil remains of long-extinct sea monsters waiting to be discovered in New Zealand and elsewhere in the Southern Hemisphere,” says Kear.
Original fossil of the New Zealand nothosaur vertebra. The oldest sea-going reptile from the Southern Hemisphere. Image by Benjamin Kear
Computerised tomography image of the New Zealand nothosaur vertebra. The oldest sea-going reptile from the Southern Hemisphere. Image by Aubrey Roberts.
Reconstruction of the New Zealand nothosaur. The oldest sea-going reptile from the Southern Hemisphere. Artwork by Johan Egerkrans
The New Zealand nothosaur fossil is held in the National Palaeontological Collection at GNS Science in New Zealand.
Article: Kear, B.P., Roberts, A.J., Young, G., Terezow, M., Mantle, D.J., Barros, I.S. & Hurum, J.H. 2024. Oldest southern sauropterygian reveals early marine reptile globalization. Current Biology 34, R1-R3. DOI: 10.1016/j.cub.2024.03.035
For further information:
Dr Benjamin Kear, Curator of Vertebrate Palaeontology and Researcher in Palaeontology at The Museum of Evolution, Uppsala University. Tel: +46 70-818 87 82 Email: benjamin.kear@em.uu.se
JOURNAL
Current Biology
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Oldest southern sauropterygian reveals early marine reptile globalization
ARTICLE PUBLICATION DATE
17-Jun-2024
No bones about it: 100-million-year-old bones reveal new species of pterosaur
CURTIN UNIVERSITY
IMAGE:
HALISKIA PETERSENI
view moreCREDIT: BY GABRIEL UGUETO
New Curtin University-led research has identified 100-million-year-old fossilised bones discovered in western Queensland as belonging to a newly identified species of pterosaur, which was a formidable flying reptile that lived among the dinosaurs.
Unearthed in 2021 by Kronosaurus Korner museum curator Kevin Petersen, the fossilised remains have been found to belong to Haliskia peterseni, a new genus and species of anhanguerian pterosaur.
Based on the shape of its skull, arrangement of teeth and shape of the shoulder bone, a research team led by PhD student Adele Pentland, from Curtin’s School of Earth and Planetary Sciences, identified the specimen as an anhanguerian, which is a group of pterosaurs known to have lived across the world, including in what is now Brazil, England, Morocco, China, Spain and the United States.
“With a wingspan of approximately 4.6m, Haliskia would have been a fearsome predator around 100 million years ago when much of central western Queensland was underwater, covered by a vast inland sea and globally positioned about where Victoria’s southern coastline is today,” Ms Pentland said.
“Careful preparation by Mr Petersen has provided the remains of the most complete specimen of an anhanguerian, and of any pterosaur, discovered in Australia to date.
“Haliskia is 22 per cent complete, making it more than twice as complete as the only other known partial pterosaur skeleton found in Australia.
“The specimen includes complete lower jaws, the tip of the upper jaw, 43 teeth, vertebrae, ribs, bones from both wings and part of a leg. Also present are very thin and delicate throat bones, indicating a muscular tongue, which helped during feeding on fish and cephalopods.”
Haliskia peterseni joins several significant marine fossil specimens on display at Kronosaurus Korner, including Kronosaurus queenslandicus, the largest marine reptile with a skull at least 2.4m long, the most complete plesiosaur from Australia and bones from the plesiosaur Eromangasaurus and the ichthyosaur Platypterygius.
Mr Petersen said this latest discovery was an exciting boost for science, education and regional tourism.
“I’m thrilled that my discovery is a new species, as my passion lies in helping shape our modern knowledge of prehistoric species,” Mr Petersen said.
The full study titled ‘Haliskia peterseni, a new anhanguerian pterosaur from the late Early Cretaceous of Australia’ will be published in the journal Scientific Reports/Springer Nature (doi.org/10.1038/s41598-024-60889-8).
JOURNAL
Scientific Reports
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Animal tissue samples
ARTICLE TITLE
Haliskia peterseni, a new anhanguerian pterosaur from the late Early Cretaceous of Australia’
ARTICLE PUBLICATION DATE
12-Jun-2024
Discovery of the microfossil Qingjiangonema from the 518-million-year-old Qingjiang biota sheds light on the adaptive evolution of sulfate-reducing bacteria in response to oxygenation in Earth’s history
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(A) OPTICAL PHOTOGRAPH OF A SOFT-BODIED MACROFOSSIL (SPECIMEN NO. CY266) OF UNKNOWN AFFINITY, WITH ABUNDANT FILAMENTOUS MICROFOSSILS OF Q. CAMBRIA (B–G) PRESENT ON THE SURFACE. (B) SEM IMAGE OF ROD-SHAPED CELLS, PHOTOGRAPHED AFTER ACID MACERATION, SHOWING EQUIMORPHIC AND EQUIDIMENSIONAL MICROCRYSTALS WITHIN EACH CELL. (C) SEM IMAGE, SHOWING A CELL EMBEDDED IN CLAYSTONE SEDIMENTS. (D, E) BSEM IMAGES, SHOWING MULTICELLULAR FILAMENTS. (F) SEM IMAGE OF A FOUR-CELL FILAMENT, SHOWING ELONGATED CELLS WITH A DIVISION GROOVE AT THE MID LENGTH (ARROWS). (I) BSEM IMAGE OF A FILAMENT COMPOSED OF CELLS OF VARIABLE LENGTH; NOTE CONSTRICTIONS BETWEEN NEIGHBORING CELLS.
view moreCREDIT: ©SCIENCE CHINA PRESS
Microbial sulfate reduction dating back to the Paleoarchean plays a crucial role in driving global carbon and sulfur cycles in ancient and modern Earth. Over 150 species of sulfate reducers from bacterial and archaeal phyla have been identified across a range of different environments. However, their origin is elusive and unequivocal fossils are lacking. Recently, a 518-million-year-old microbial fossil from China identified as an ancient sulfate-reducing bacterium sheds light on the adaptive evolution of sulfate-reducing bacteria in response to Earth’s oxygenation events. This new fossil, named as Qingjiangonema cambria, is reported by a research team led by Prof. Xingliang Zhang from the Shaanxi Key Laboratory of Early Life and Environments at Northwest University, Prof. Jinhua Li from the Institute of Geology and Geophysics of the Chinese Academy of Sciences (IGGCAS) and Prof. Yinzhao Wang from the School of Life Sciences and Biotechnology at Shanghai Jiao Tong University.
Qingjiangonema was discovered in black shales of the Shuijingtuo Formation that yields the Qingjiang biota, an early Cambrian Burgess Shale–type (BST) fossil Lagerstätte of South China. And it appears as a long filament comprising hundreds of rod-shaped cells. Cells are constricted at junctions, ∼1 to 3 μm wide and ∼0.8 to 11.0 μm long. Each cell is externally enveloped by a trilaminar ultrathin film and internally filled by equimorphic and equidimensional pyrite microcrystals. The unique chain-like morphology and its presence in black shales (cemented anoxic mud), provide crucial clues to determine the biological affinity of Qingjiangonema. The faithful replication of cell morphology by pyrite microcrystals infilling suggests that Qingjiangonema be able to precipitate minerals intracellularly when it was alive.
To further determine the physiology of Qingjiangonema, in situ sulfur isotope analyses of intracellular pyrite microcrystals using Secondary Ion Mass Spectroscopy (SIMS) were carried out, and the result shows the intracellular pyrite microcrystals have a light sulfur isotope composition and large isotopic fractionation which are comparable to that of the modern Desulfonema in anoxic mud.
Interestingly, among the vast array of modern sulfate-reducing bacteria and their relatives, only the members of Desulfonema and cable bacteria within the phylum Desulfobacterota exhibit similar chain-like morphologies. Desulfonema species are filamentous sulfate reducers characterized by reducing sulfate under anoxic condition with a large sulfur isotope fractionation from sulfate to sulfide. The cable bacteria, however, are opposite in metabolism. They are aerobic sulfide-oxidizing bacteria well-known for long-distance electron transport over centimeter-scale distances and share canonical sulfate-reducing genes with the members in Desulfobacterota.
Overall, multiple lines of evidence including fossil morphology, living condition assessment and isotope analyses demonstrate that Qingjiangonema was a filamentous multicellular sulfate-reducing microfossil.
The discovery of this remarkable microfossil sheds light on the evolution of sulfate-reducing bacteria and cable bacteria. Phylogenomic and molecular clock analyses confirm an independent origin of multicellularity of Desulfonema and cable bacteria within the phylum Desulfobacterota. More importantly, these molecular biological analyses infer that Desulfobacterota, encompassing majorities of sulfate-reducing taxa, diverged ~2.4 billion years ago during the Paleoproterozoic Great Oxygenation Event (GOE), while cable bacteria diverged ~0.56 billion years ago during or after Neoproterozoic Oxygenation Event.
Taking together, the authors considered that Qingjiangonema cambria is either akin to Desulfonema or represents a sulfate-reducing ancestor to cable bacteria. They proposed that sulfate-reducing bacteria were firstly diversified in response to the increase of oceanic sulfate concentrations during the GOE and that sulfur-oxidizing cable bacteria evolved from a filamentous multicellular sulfate-reducing ancestor by reversal of the sulfate reduction pathway when large areas of the seafloor became oxygenated during or after the NOE.
See the article:
The Cambrian microfossil Qingjiangonema reveals the co-evolution of sulfate-reducing bacteria and the oxygenation of Earth’s surface
Ultrastructures of the microfossil Qingjiangonema cambria.
(a, b) SEM images of a Q. cambria on the macrofossil in Fig. 2a, indicating FIB milling positions of longitudinal and cross sections, respectively. (c) STEM-HAADF image of the ultrathin cross section in (b), showing microcrystals tightly packed within a thin envelope. (d) STEM-HAADF image of the ultrathin longitudinal section in (a), showing that neighboring cells are disconnected with intercellular boundaries, note that microcrystals are much smaller in the smaller cell than those in the larger neighboring cells. (e) Close-up of the boxed area in (c), showing the ultra-thin, multilayered film comparable to the typical cell envelope of Gram-negative bacteria, which comprises a cytoplasmic membrane (CM), a periplasmic space (PS) and an outer membrane (OM).
(a) Time tree of the major lineages of the phylum Desulfobacterota, with the sulfate-reducing Desulfonema and sulfide-oxidizing cable bacteria falling in two separate linages. (b) Evolution of Earth’s atmospheric oxygen content through time, PAL = present atmospheric level. (c) Simplified estimate for the history of seawater sulfate concentrations. Shaded areas crossing (a) to (c) represent time intervals of GOE and NOE, respectively, highlighting the coincidence between phylogenetic evolution of the sulfate-reducing bacteria and major increases of Earth’s atmospheric oxygen content as well as oceanic sulfate concentrations.
CREDIT
©Science China Press
JOURNAL
Science Bulletin
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