Science
New long-necked dinosaur helps rewrite evolutionary history of sauropods in South America – University of Michigan News
A medium-sized sauropod dinosaur inhabited the tropical lowland forested area of the Serranía del Perijá in northern Colombia approximately 175 million years ago, according to a new study by an international team of researchers published in the Journal of Vertebrate Paleontology.
The new species is a long-necked, plant-eating dinosaur known from a single trunk vertebra that is about a half meter tall and wide. The vertebra bears a distinct pattern of bony struts that identify it as the new dinosaur species Perijasaurus lapaz (pear-EE-hah-SOW-roos la-PAHZ)—named in recognition of the mountainous region where it was found and for the 2016 peace treaty that allowed scientists to pursue their research decades after the fossil remains were found in 1943.
Perijasaurus is the northernmost occurrence of a sauropod in South America and represents an early phase in their evolutionary history.
“This new genus and species in the paleotropics allows us to understand a little more about the origin of the sauropods in the Jurassic, as well as how they set the stage for later sauropods from the Cretaceous,” said study lead author Aldo Rincón Burbano, professor of physics and geosciences at the Universidad del Norte in Colombia.
The fossil was first discovered in 1943 during a geological mapping campaign by the Tropical Oil Company. The specimen was taken to the collections of University of California, Berkeley and preliminarily described in 1955.
University of Michigan paleontology curator and professor Jeff Wilson Mantilla examined the specimen as a graduate student in 1997 and later developed a project supported by the Fulbright Foundation to study early sauropod evolution in Colombia.
As part of that project, the Colombian specimen was loaned to U-M, where chief preparator William Sanders removed glues and plaster, greatly increasing the visibility of anatomical details and reducing the total weight of the sample.
“Following repreparation of the fossil, we were able to better visualize the delicate bony laminae that interconnect the projecting parts of the vertebra—the spine, the intervertebral articulations, the rib articulations—the architecture of those connections provides critical morphological information that identifies it as a new species and places it within the sauropod family tree,” Wilson Mantilla said.
A 3D model of the specimen is hosted on the University of Michigan Online Repository of Fossils.
A conflict since 1964 between the Colombian military forces, the FARC guerrilla group and paramilitary groups made it unsafe to conduct research in Serranía del Perijá, near the border between Colombia and Venezuela, until the peace agreements in 2016.
Since then, the research team has been working to determine with higher precision where the fossil was found. A satellite image of the region was superimposed upon a hand-drawn map from 1955 showing the location of the fossil. A further clue was provided by sediment removed from the vertebra itself during the preparation process—allowing the team to determine the specific layer from which the bone was
collected. Fieldwork at the site and neighboring localities helped to reconstruct the paleoenvironment the dinosaur inhabited.
“Perijasaurus lived in an environment of low slopes associated with a river and a forested area. We found fine sand and leaf debris in the sediment deposited in the area where the vertebra was originally found, and it is consistent with the sediment within the neural arch of the vertebra, which are only preserved near a floodplain, i.e., near the slopes of a river, a wooded area,” said Daniel Raad, a former geology student at the Universidad del Norte.
Most of the discoveries of dinosaurs in South America come from rocks from the Cretaceous period located in Argentina and Brazil. Dinosaurs from the northern part of South America are much rarer, particularly during the Jurassic and Triassic periods, during the initial radiation of dinosaurs, when landmasses were still substantially interconnected.
“Although Perijasaurus is represented by a single vertebra, that region of the skeleton provides the most information in sauropods, due to a series of laminae and other structures,” said Martín Ezcurra, a paleontologist and associate researcher of the CONICET (Argentina’s National Council for Scientific and Technical Research) and head curator of paleovertebrates at the Argentine Museum of Natural Sciences.
The researchers were able to determine the evolutionary relationships of Perijasaurus through a computational analysis focusing on Early and Middle Jurassic sauropods.
“Perijasaurus is part of the early radiation of sauropods, which includes species from southern South America, Africa, Asia and Europe,” said Harold Jiménez Velandia, a geologist at the University of Caldas.
The presence of Perijasaurus in the paleotropics of South America, together with its close phylogenetic relationship with geographically widespread species that inhabited low latitudes, suggests that sauropods diversified and dispersed fairly rapidly following a major anoxic event at the end of the Lower Jurassic, when portions of the oceans were depleted of oxygen over large geographic areas.
“What we see in the Early Jurassic, both in high latitudes and in the most tropical areas, is that sauropod species were evolutionarily and geographically interconnected, which is something that had also been seen with other groups of carnivorous and herbivorous dinosaurs,” Ezcurra said.
Sauropods are the largest animals to have walked on land, some reaching estimated lengths of 49 meters and weights of up to 57 metric tons. Their ability to support their weight and move their bodies efficiently stems from a series of adaptations to reduce weight and increase bony support.
An anatomical hallmark of sauropods is vertebral pneumaticity. Essentially, extensions of the air-sac system of the lungs extend into the vertebral column and actually remove internal bone, effectively lightening the skeleton.
“By the Late Jurassic, sauropods had evolved highly pneumatic vertebrae riddled with air spaces that removed one-half to three-quarters the bone weight. Perijasaurus represents an evolutionary antecedent in which the pneumatic invasions are much simpler and more limited in extent, removing less than a quarter of bone volume,” Wilson Mantilla said.
He said the team will continue to focus on regions of Colombia that have exposures of Jurassic sediments.
“Colombia is emerging as a country with great potential to contribute to the paleontology of the continent and the world,” Wilson Mantilla said.
Perijasaurus is permanently stored at the University of California Museum of Paleontology in Berkeley, California. The research was funded by the Fulbright Foundation, Universidad del Norte, Sam Welles Fund and CONICET.
An international team of researchers has used the NASA/ESA/CSA James Webb Space Telescope to measure the temperature of the rocky exoplanet TRAPPIST-1 b. The measurement is based on the planet’s thermal emission: heat energy given off in the form of infrared light detected by Webb’s Mid-Infrared Instrument (MIRI). The result indicates that the planet’s dayside has a temperature of about 500 kelvins (roughly 230°C), and suggests that it has no significant atmosphere. This is the first detection of any form of light emitted by an exoplanet as small and as cool as the rocky planets in our own solar system. The result marks an important step in determining whether planets orbiting small active stars like TRAPPIST-1 can sustain atmospheres needed to support life. It also bodes well for Webb’s ability to characterise temperate, Earth-sized exoplanets using MIRI.
“These observations really take advantage of Webb’s mid-infrared capability,” said Thomas Greene, an astrophysicist at NASA’s Ames Research Center and lead author on the study published today in the journal Nature. “No previous telescopes have had the sensitivity to measure such dim mid-infrared light.”
Rocky planets orbiting ultra cool red dwarfs
In early 2017, astronomers reported the discovery of seven rocky planets orbiting an ultracool red dwarf star (or M dwarf) 40 light-years from Earth. What is remarkable about the planets is their similarity in size and mass to the inner, rocky planets of our own solar system. Although they all orbit much closer to their star than any of our planets orbit the Sun – all could fit comfortably within the orbit of Mercury – they receive comparable amounts of energy from their tiny star.
TRAPPIST-1 b, the innermost planet, has an orbital distance about one hundredth that of Earth’s and receives about four times the amount of energy that Earth gets from the Sun. Although it is not within the system’s habitable zone, observations of the planet can provide important information about its sibling planets, as well as those of other M-dwarf systems.
“There are ten times as many of these stars in the Milky Way as there are stars like the Sun, and they are twice as likely to have rocky planets as stars like the Sun,” explained Greene. “But they are also very active – they are very bright when they’re young and they give off flares and X-rays that can wipe out an atmosphere.”
Co-author Elsa Ducrot from CEA in France, who was on the team that conducted the initial studies of the TRAPPIST-1 system, added, “It’s easier to characterise terrestrial planets around smaller, cooler stars. If we want to understand habitability around M stars, the TRAPPIST-1 system is a great laboratory. These are the best targets we have for looking at the atmospheres of rocky planets.”
Detecting an atmosphere (or not)
Previous observations of TRAPPIST-1 b with the NASA/ESA Hubble Space Telescope, as well as NASA’s Spitzer Space Telescope, found no evidence for a puffy atmosphere, but were not able to rule out a dense one.
One way to reduce the uncertainty is to measure the planet’s temperature. “This planet is tidally locked, with one side facing the star at all times and the other in permanent darkness,” said Pierre-Olivier Lagage from CEA, a co-author on the paper. “If it has an atmosphere to circulate and redistribute the heat, the dayside will be cooler than if there is no atmosphere.”
Astronomers used Webb’s Mid-Infrared Instrument (MIRI) to measure the brightness of mid-infrared light. When the planet is beside the star, the light emitted by both the star and the dayside of the planet reach the telescope, and the system appears brighter. When the planet is behind the star, the light emitted by the planet is blocked and only the starlight reaches the telescope, causing the apparent brightness to decrease.
Astronomers can subtract the brightness of the star from the combined brightness of the star and planet to calculate how much infrared light is coming from the planet’s dayside. This is then used to calculate the dayside temperature.
The graph shows combined data from five separate observations made using MIRI’s F1500W filter, which only allows light with wavelengths ranging from 13.5-16.6 microns to pass through to the detectors. The blue squares are individual brightness measurements. The red circles show measurements that are “binned,” or averaged to make it easier to see the change over time. The decrease in brightness during the secondary eclipse is less than 0.1%. MIRI was able to detect changes as small as 0.027% (or 1 part in 3700).
This is the first thermal emission observation of TRAPPIST-1 b, or any planet as small as Earth and as cool as the rocky planets in the Solar System.
The observations are being repeated using a 12.8-micron filter in order to confirm the results and narrow down the interpretations.
MIRI was developed as a partnership between Europe and the USA: the main partners are ESA, a consortium of nationally funded European institutes, the Jet Propulsion Laboratory (JPL) and the University of Arizona. The instrument was nationally funded by the European Consortium under the auspices of the European Space Agency.
[Image description: At the top of the infographic is a diagram showing a planet moving behind its star (a secondary eclipse). Below the diagram is a graph showing the change in brightness of 15-micron light emitted by the star-planet system over the course of 3.5 hours. The infographic shows that the brightness of the system decreases markedly as the planet moves behind the star.]
Credit:
NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA)
The team used a technique called secondary eclipse photometry, in which MIRI measured the change in brightness from the system as the planet moved behind the star. Although TRAPPIST-1 b is not hot enough to give off its own visible light, it does have an infrared glow. By subtracting the brightness of the star on its own (during the secondary eclipse) from the brightness of the star and planet combined, they were able to successfully calculate how much infrared light is being given off by the planet.
Measuring minuscule changes in brightness
Webb’s detection of a secondary eclipse is itself a major milestone. With the star more than 1,000 times brighter than the planet, the change in brightness is less than 0.1%.
“There was also some fear that we’d miss the eclipse. The planets all tug on each other, so the orbits are not perfect,” said Taylor Bell, the post-doctoral researcher at the Bay Area Environmental Research Institute who analysed the data. “But it was just amazing: The time of the eclipse that we saw in the data matched the predicted time within a couple of minutes.”
Analysis of data from five separate secondary eclipse observations indicates that TRAPPIST-1 b has a dayside temperature of about 500 kelvins, or roughly 230°C. The team thinks the most likely interpretation is that the planet does not have an atmosphere.
The dayside brightness of TRAPPIST-1 b at 15 microns corresponds to a temperature of about 500 K (roughly 230°C). This is consistent with the temperature assuming the planet is tidally locked (one side facing the star at all times), with a dark-coloured surface, no atmosphere, and no redistribution of heat from the dayside to the nightside.
If the heat energy from the star were distributed evenly around the planet (for example, by a circulating carbon dioxide-free atmosphere), the temperature at 15 microns would be 400 K (125°C). If the atmosphere had a substantial amount of carbon dioxide, it would emit even less 15-micron light and would appear to be even cooler.
Although TRAPPIST-1 b is hot by Earth standards, it is cooler than the dayside of Mercury, which consists of bare rock and no significant atmosphere. Mercury receives about 1.6 times more energy from the Sun than TRAPPIST-1 b does from its star.
MIRI was developed as a partnership between Europe and the USA: the main partners are ESA, a consortium of nationally funded European institutes, the Jet Propulsion Laboratory (JPL) and the University of Arizona. The instrument was nationally funded by the European Consortium under the auspices of the European Space Agency.
[Image description: Infographic titled, “Rocky Exoplanet TRAPPIST-1 b Dayside Temperature Comparison, MIRI F1500W” showing five planets plotted along a horizontal temperature scale: Earth, TRAPPIST-1 b, Mercury, and two different models of TRAPPIST-1 b.]
Credit:
NASA, ESA, CSA, J. Olmsted (STScI), T. P. Greene (NASA Ames), T. Bell (BAERI), E. Ducrot (CEA), P. Lagage (CEA)
“We compared the results to computer models showing what the temperature should be in different scenarios,” explained Ducrot. “The results are almost perfectly consistent with a blackbody made of bare rock and no atmosphere to circulate the heat. We also didn’t see any signs of light being absorbed by carbon dioxide, which would be apparent in these measurements.”
This research was conducted as part of Guaranteed Time Observation (GTO) program 1177, which is one of eight approved GTO and General Observer (GO) programs designed to help fully characterise the TRAPPIST-1 system. Additional secondary eclipse observations of TRAPPIST-1 b are currently in progress, and now that they know how good the data can be, the team hopes to eventually capture a full phase curve showing the change in brightness over the entire orbit. This will allow them to see how the temperature changes from the day to the nightside and confirm if the planet has an atmosphere or not.
“There was one target that I dreamed of having,” said Lagage, who worked on the development of the MIRI instrument for more than two decades. “And it was this one. This is the first time we can detect the emission from a rocky, temperate planet. It’s a really important step in the story of discovering exoplanets.”
This is not a true planetary alignment where they will appear in a straight line, but NASA scientist Bill Cooke told CBS News that the planets will be visible on March 28 and that the “alignment: will look “very pretty.”
How to watch the 5 planets
While the five planets should technically be visible along with the waxing crescent moon in most parts of the world, you will not be able to see it unless you are in a location with an unobstructed view of the horizon.
According to Rick Feinberg, senior contributing editor at Sky & Telescope magazine, Venus and Mars should be easy to spot. Venus is the brightest planet in the solar system and will be high in the sky, and Mars will shine brightly next to the waxing Moon. But on the other hand, Uranus, which will appear near Venus, will appear faint and will only be visible next.
“Wait until the sun has set and then go out and look low in that bright part of the sky where the sun has just set with binoculars, and you should see brighter Jupiter next to fainter Mercury,” said Fienberg to NPR.
In order to get the best view of this rare celestial event, go to a location with as little light pollution as possible and a clear horizon with not obstructions. Once there, you should be able to spot most planets, apart from Jupiter and Mercury, without the use of binoculars.
Is this a rare event?
While tonight is not an everyday event, it is not truly a five-planet alignment since the planets will not appear as if they form a single straight line.
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If you were looking for an actual alignment of five planets, that time has passed. A true 5 planet alignment happened in June last year when Mercury, Venus, Mars, Jupiter and Saturn stretched across the sky from low in the east to higher in the south in the order of their distance from the Sun.
Even discounting the rare coincidence where they appeared in that particular order, the planetary alignment in June was the first one in nearly eighteen years, with the last time being on December 2004. Such an event is not expected to happen again until 2040, according to NPR.
MOSCOW –
A Russian space capsule safely returned to Earth without a crew Tuesday, months after it suffered a coolant leak in orbit.
The Soyuz MS-22 leaked coolant in December while attached to the International Space Station. Russian space officials blamed the leak on a tiny meteoroid that punctured the craft’s external radiator. They launched an empty replacement capsule last month to serve as a lifeboat for the crew.
The damaged capsule safely landed Tuesday under a striped parachute in the steppes of Kazakhstan, touching down as scheduled at 5:45 p.m. (7:45 a.m. EDT) 147 kilometres (91 miles) southeast of Zhezkazgan under clear blue skies.
Space officials determined it would be too risky to bring NASA’s Frank Rubio and Russia’s Sergey Prokopyev and Dmitri Petelin back in the Soyuz in March as originally planned, as cabin temperatures would spike with no coolant, potentially damaging computers and other equipment, and exposing the suited-up crew to excessive heat.
The three launched in September for what should have been a six-month mission on the International Space Station. They now are scheduled to return to Earth in September in a new Soyuz that arrived at the space outpost last month with no one on board, meaning the trio will spend a year in orbit.
Also on the station are NASA astronauts Stephen Bowen and Woody Hoburg, the United Arab Emirates’ Sultan Alneyadi, and Russia’s Andrey Fedyaev.
A similar coolant leak was spotted in February on the Russian Progress MS-21 cargo ship docked at the space outpost, raising suspicions of a manufacturing flaw. Russian state space corporation Roscosmos ruled out any defects after a check and concluded that both incidents resulted from hits by meteoroids.
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