Were dinosaurs already undergoing a long-term decline before an asteroid hit at the end of the Cretaceous about 65.5 million years ago? A new study led by Museum scientists gives a multifaceted answer.
The findings, published online today in the journal Nature Communications, suggest that in general, large-bodied, “bulk-feeding” herbivores were declining during the last 12 million years of the Cretaceous Period. But carnivorous dinosaurs and mid-sized herbivores were not.
“Few issues in the history of paleontology have fueled as much research and popular fascination as the extinction of non-avian dinosaurs,” said lead author Steve Brusatte, a Columbia University graduate student affiliated with the Museum’s Division of Paleontology. “Did sudden volcanic eruptions or an asteroid impact strike down dinosaurs during their prime? We found that it was probably much more complex than that, and maybe not the sudden catastrophe that is often portrayed.”
The research team, which includes Brusatte; Mark Norell, chair of the Museum’s Division of Paleontology; and scientists Richard Butler of Ludwig Maximilian University of Munich and Albert Prieto-Márquez from the Bavarian State Collection for Palaeontology, both in Germany, is the first to look at dinosaur extinction based on “morphological disparity”—the variability of body structure within particular groups of dinosaurs. Read more »
Ichthyologist John Sparks, curator of Creatures of Light: Nature’s Bioluminescence, recalls two challenging expeditions in Madagascar in search of new species of blind cavefishes. Read an excerpt of the interview below.
We were in Ankarana Reserve in far northern Madagascar, a surreal landscape of exposed karst formations. These are one-of-a-kind formations of permeable rocks, with rivers and streams in between. It’s kind of like Swiss cheese, with water running through it. We were looking for a species of blind cavefish endemic to this region.
But first, we had to make our way through the piles of bat guano [dung]. The cavefishes, which lack pigment and have no eyes, eat some of the invertebrates that are in the water, but a lot of them survive mainly on guano. There are enormous piles of it in these caves, 20- to 30-foot mounds. When you get closer, the mounds seem to come alive, with millions of clicking, rustling cockroaches that run over your feet and up your legs. It’s just like a scene out of an Indiana Jones movie. Read more »
From fireflies to jellyfishes, an astonishing range of animals create their own light. On Sunday, April 22, kids can explore activity carts about glowing organisms while scientists David Gruber, Marc Branham, and Edith Widder share their research about these creatures and the deep-sea vehicles and cameras required to study them. David Gruber, an assistant professor at The City University of New York (CUNY) and a Museum research associate who consulted on the exhibition Creatures of Light: Nature’s Bioluminescence, recently answered a few questions about his deep-sea photography and the Museum.
What was it like consulting on Creatures of Light?
David Gruber: One of the best parts was meeting with the designers who made the models of organisms. We would make tiny tweaks until they got more and more realistic, and we created some of the most detailed models of several organisms. As the models were being designed, many anatomy questions came up that weren’t anywhere in the scientific literature, so we often went back to the animals themselves to answer questions the designers brought up.
Part of your work for the exhibition involved photographing a coral wall. Were some of these animals harder to photograph than others?
Gruber: Unlike corals that sit in place, the fish are harder because they move around. One of the animals people will see is a glowing eel that jumped into one of our photographs. We didn’t even know it was there until we got back to lab and reviewed the film. Read more »
Research led by Museum scientists shows that ammonites, an extinct type of shelled mollusk that’s closely related to modern-day nautiluses and squids, made homes in the unique environments surrounding methane seeps in the seaway that once covered America’s Great Plains. The findings, recently published in the journal Geology, provide new insights into the mode of life and habitat of these ancient animals.
In the Black Hills region of South Dakota, researchers are investigating a 74-million-year-old mound of fossilized material where methane-rich fluids once migrated through the sediments onto the sea floor. When the face of this cliff recently slumped off, a wide variety of bivalves, sponges, corals, fish, crinoids, and, as recently documented, ammonites, were revealed.
Studying these well-preserved shells, the researchers tried to determine the role of ammonites in the unique seep ecosystem. By analyzing the abundance of isotopes (alternative forms) of carbon, oxygen, and strontium, the group made a surprising discovery. The ammonites at the seep, once thought to be transient, had spent their whole lives there. The seeps also likely attracted large clusters of plankton, the ammonites’ preferred prey. Read more »
Only one group of animals, the deep-sea fishes of the genus Linophryne, is known to glow using two different processes: by producing their own light and by broadcasting the glimmer of a cooperative colony of bioluminescent bacteria. Several species shine to attract both prey and partner, a much-smaller male who attaches to his mate using his jaws and proceeds to fertilize her eggs while receiving nourishment in return.
An anglerfish’s lure-like esca, named for the Latin word for “bait,” is a bulb that glows with light provided by bacteria. Other marine animals such as ponyfishes and flashlight fishes also rely on such symbiotic relationships for light. Anglerfish species such as Linophryne algibarbata boast elaborate glowing strands that radiate from the fish’s chin, where a chemical reaction generates energy that is thrown off as light.
