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Trilobites' growth may have resembled that of modern marine crustaceans – Phys.org

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A Triarthrus eatoni trilobite, order Ptychopariida, family Olenidae, 11 mm long, found in the Frankfort Shale, New York, USA, from the Upper Ordovician. Credit: Dwergenpaartje / Wikimedia / CC BY-SA 3.0

Trilobites, extinct marine arthropods that roamed the world’s oceans from about 520 million years ago until they went extinct 250 million years ago at the end of the Permian period, may have grown in a similar fashion and reached ages that match those of extant crustaceans, a new study has found.

In a paper published in the journal Paleobiology, researchers from the University of British Columbia and Uppsala University show that the Ordovician trilobite Triarthrus eatoni, some 450 million years ago, reached a length of just above 4 cm in about 10 years, with a growth curve very similar to that of small, slow-growing crustaceans.

“T. eatoni lived in low-oxygen environments and, similarly to extant crustaceans exposed to , exhibited low growth rates compared with growth under more oxygenated conditions,” said Daniel Pauly, principal investigator of UBC’s Sea Around Us initiative and lead author of the study. “Low-oxygen environments make is more difficult for water-breathers to grow, and add to the difficulties of breathing through gills, which, as 2D surfaces, cannot keep up with the growth of their 3D bodies. Thus, under hypoxic conditions, they must remain small if they are to maintain the rest of their body functions.”

In the case of trilobites, their exopods—external branches on the upper part of their limbs—functioned as gills. Thus, these ancient animals had similar growth constraints to those of their modern counterparts.

To reach these conclusions, Pauly and his colleague from Uppsala University, paleontologist James Holmes, resorted to the analysis of length-frequency data, a method developed within and for studying the growth of fish and invertebrates lacking the physical markings that indicate their age.

The information to perform their analysis was obtained from an earlier publication with of the length frequency distribution of 295 exceptionally-preserved fossils collected at “Beecher’s Trilobite Bed’ in New York State.

After estimating the parameters of a growth model widely used in fisheries science, the von Bertalanffy growth function, the researchers compared their results with published data on the growth of extant crustaceans. They found that the growth parameters they estimated for Triarthrus eatoni were well within the range of recent, slow-growing crustaceans.

“These findings provide the first reasonable estimates of absolute growth in early animals using methods known to accurately characterize growth in comparable living species,” Holmes said. “They show us that nearly half-a-billion years ago, growth in marine arthropods like trilobites was similar to modern examples like crustaceans living in today’s oceans.”


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450-million-year-old sea creatures had a leg up on breathing


More information:
Daniel Pauly et al, Reassessing growth and mortality estimates for the Ordovician trilobite Triarthrus eatoni, Paleobiology (2022). DOI: 10.1017/pab.2022.22

Citation:
Trilobites’ growth may have resembled that of modern marine crustaceans (2022, July 25)
retrieved 26 July 2022
from https://phys.org/news/2022-07-trilobites-growth-resembled-modern-marine.html

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SpaceX delivers Russian, Native American women to station – CTV News

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CAPE CANAVERAL, Fla. –

A Russian cosmonaut who caught a U.S. lift to the International Space Station arrived at her new home Thursday for a five-month stay, accompanied by a Japanese astronaut and two from NASA, including the first Native American woman in space.

The SpaceX capsule pulled up to the station a day after launching into orbit. The linkup occurred 260 miles (420 kilometers) above the Atlantic, just off the west coast of Africa.

It was the first time in 20 years that a Russian hitched a ride from NASA’s Kennedy Space Center, the result of a new agreement reached despite friction over the war in Ukraine.

Cosmonaut Anna Kikina joins two Russians already at the orbiting outpost. She’ll live and work on the Russian side until March, before returning to Earth in the same SpaceX capsule.

Riding along with Kikina: Marine Col. Nicole Mann, a member of the Wailacki of the Round Valley Indian Tribes in California, Navy Capt. Josh Cassada and Japan’s Koichi Wakata, the only experienced space flier of the bunch with five missions.

As the capsule closed in, the space station residents promised the new arrivals that their bunks were ready and the outside light was on.

“You guys are the best,” replied Mann, the capsule’s commander.

Mann and her crew will replace three Americans and one Italian who will return in their own SpaceX capsule next week after almost half a year up there. Until then, 11 people will share the orbiting lab.

NASA astronaut Frank Rubio arrived two weeks ago. He launched on a Soyuz rocket from Kazakhstan, kicking off the cash-free crew swapping between NASA and the Russian Space Agency. They agreed to the plan last summer in order to always have an American and Russian at the station.

Until Elon Musk’s SpaceX started launching astronauts two years ago, NASA was forced to spend tens of millions of dollars every time an astronaut flew up on a Soyuz.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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NASA Wants To Mine The Moon, But Law Experts Say It's Not That Simple – SlashGear

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The first roadblock facing humans as we seek to expand our presence in the solar system lies in technology. NASA reports that it takes about seven months (measured in Earth days) to travel from our planet’s surface to Mars. Thrillist notes that travel to the Moon only requires a three-day journey, while exploration of Jupiter or Saturn (the next bodies out from Mars) would require a lengthy, six- or seven-year voyage, respectively. On a technical level, our current means of launching satellites and humans at these distant bodies is exactly that, a launch (via NASA). In order to make space travel more feasible for human explorers, we would need to develop a propulsion system that could continually deliver powered flight to a spacecraft, or at least the ability to continually augment flight speed, rather than simply relying on initial launch velocity to carry the craft along to its final destination.

This means a combination of two distinct realities: Humans must develop a brand new means of propulsion that requires far less storage space and mass, a revolutionary idea to be sure; and we must develop the ability to hop between planets and refuel along this lengthy journey. Therefore, technological advancement that would support increased space travel would require both colonization and a capacity for extracting mineral resources from the surfaces of neighboring planets and moons. Continuous habitation in new worlds would be required to support these efforts.

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Good planning gets the bike rolling – Science Daily

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In surveys, a large majority of respondents usually agree that cycling can make a significant contribution to reducing greenhouse gases and to sustainable transport, especially in densely populated areas. In contrast, for many countries in reality there is a large gap between desired and actual numbers. In Germany, for example, only 20% of the short-distance of everyday trips in residential environments are covered by bicycle.

When asked about the reasons, one point repeatedly comes up top of the list: The perceived or actual lack of safety on the bike routes used. Increasing the share of cycling trips in the modal split thus depends crucially on a well-developed bike path infrastructure. However, designing efficient bike path networks is a complex problem that involves balancing a variety of constraints while meeting overall cycling demand. In addition, many municipalities still only have small budgets available for improving bicycle infrastructure.

In their study, researchers from the Chair of Network Dynamics / Center for Advancing Electronics Dresden (cfaed) at TU Dresden propose a new approach to generate efficient bike path networks. This explicitly considers the demand distribution and route choice of cyclists based on safety preferences. Typically, minimizing the travel distance is not the only goal, but aspects such as (perceived) safety or attractiveness of a route are also taken into account.

The starting point of this approach is a reversal of the usual planning process: Under real conditions, a bike path network is created by constantly adding bike paths to more streets. The cfaed scientists, on the contrary, start with an ideal, complete network, in which all streets in a city are equipped with a bike path. In a virtual process, they gradually remove individual, less used bike path segments from this network. The route selection of the cyclists is continuously updated. Thus, a sequence of bike path networks is created that is always adapted to the current usage. Each stage of this sequence corresponds to a variant that could be implemented with less financial effort. In this way, city planners can select the version that fits their municipality’s budget.

“In our study, we illustrate the applicability of this demand-driven planning scheme for dense urban areas of Dresden and Hamburg,” explains Christoph Steinacker, first author of the study. “We approach a real-life issue here using the theoretic toolbox of network dynamics. Our approach allows us to compare efficient bike path networks under different conditions. For example, it allows us to measure the influence of different demand distributions on the emerging network structures.” The proposed approach can thus provide a quantitative assessment of the structure of current and planned bike path networks and support demand-driven design of efficient infrastructures.

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Materials provided by Technische Universität Dresden. Note: Content may be edited for style and length.

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