the-scientist.com 的前十大競爭對手

newscientist.com

Unlock the following benefits with a subscription

sciencedaily.com

Parallel evolution is the independent evolution of similar traits, starting from a similar ancestral condition. Frequently this is the situation in more closely related lineages, where several species respond to similar challenges in a similar way. One of the most spectacular examples of parallel evolution is provided by the two main branches of the mammals, the placentals and marsupials, which have followed independent evolutionary pathways following the break-up of land-masses such as Gondwanaland roughly 100 million years ago. In South America, marsupials and placentals shared the ecosystem (prior to the Great American Interchange); in Australia, marsupials prevailed; and in the Old World the placentals won out. However, in all these localities mammals were small and filled only limited places in the ecosystem until the mass extinction of dinosaurs forty million years later. At this time, mammals on all three landmasses began to take on a much wider variety of forms and roles. While some forms were unique to each environment, surprisingly similar animals have often emerged in two or three of the separated continents. Examples of these include the litopterns and horses, whose legs are difficult to distinguish; the European sabre-tooth tiger (Smilodon) and the South American marsupial sabre-tooth (Thylacosmilus); the Tasmanian wolf and the European wolf; likewise marsupial and placental moles, flying squirrels, and (arguably) mice.

pnas.org

proceedings of the national academy of sciences (pnas), a peer reviewed journal of the national academy of sciences (nas) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.

phys.org

Daily science news on research developments, technological breakthroughs and the latest scientific innovations

scientificamerican.com

How a space rock vanished from Africa and showed up for sale across an ocean

sciencenews.org

Frequently asked questions about the Society for Science, memberships, Science News subscriptions, advertising opportunities, and more.

science.org

science/aaas peer-reviewed journals deliver impactful research, daily news, expert commentary, and career resources.

mdpi.com

MDPI is a publisher of peer-reviewed, open access journals since its establishment in 1996.

ncbi.nlm.nih.gov

Search all biomedical databases provided by the National Center for Biotechnology Information (NCBI), an agency of the U.S. National Library of Medicine at the NIH

scitechdaily.com

Science, Space and Technology News 2026