2022 was a busy year at the National Museum of Natural History. The museum returned to its pre-pandemic visitation hours, welcoming millions of visitors through its doors to see a host of new displays, including spectacular diamonds unearthed in America and the first Northern giant hornet nest discovered in the United States.
But much more action was taking place off exhibit, in the labyrinth of halls and labs at both the museum and its collections facility in Suitland Maryland. Here, museum staff are constantly acquiring, labeling, preserving and studying specimens that range from pressed plants and pinned butterflies to ancient fossils and massive whale bones. To kick off 2023, Smithsonian Voices is highlighting several museum research milestones from the previous year.
Read previous installments of “2022 in Review” here.
A new Jurassic reptile that scurried underfoot of dinosaurs
Wyoming’s Morrison Formation is iconic for its fossils of titanic dinosaurs like Stegosaurus, Camarasaurus and Allosaurus. But these were far from the only inhabitants of this Jurassic ecosystem. Smithsonian paleontologists Matthew Carrano and Dave DeMar recently identified the nearly complete skeleton of a 150-million-year-old reptile while examining fossils collected near an Allosaurus nest. In a study in the Journal of Systematic Paleontology, the researchers named the six-inch long reptile Opisthiamimus gregori, after museum volunteer Joseph Gregor who painstakingly prepared the remarkable fossil.
Opisthiamimus resembled a stout lizard and likely munched on Mesozoic bugs. But the new critter is actually an ancient relative of New Zealand’s tuatara, an enigmatic reptile that’s the only living member of its entire taxonomic order, Rhynchocephalia. During the Mesozoic, these reptiles were rampant and Opisthiamimus’s remarkably preserved skeleton may provide clues as to why this lost lineage was supplanted by lizards.
A bounty of new species inhabit a mineral-rich stretch of seafloor
A 3,100 mile swath of the central Pacific Ocean called the Clarion-Clipperton Zone (CCZ) is home to one of the richest assortments of potato-sized lumps of precious minerals called nodules. These nodules contain rare metals like nickel, copper and cobalt that are essential to modern technology like cellphones. As a result, this area has become a proposed hub for deep-sea mining.
But the CCZ’s submerged mountains, plains and troughs are also home to a variety of sea creatures, many of which remain undescribed. To discover what resides down here, museum zoologist Stephen Cairns and an international team of researchers deployed a remotely operated vehicle to depths as deep as nearly 17,000 feet to scour the seafloor for life. In a study published in the journal ZooKeys, they described 48 different species, including sea cucumbers, basket stars, anemones and sponges. Thirty-nine of these animals are potentially new to science.
Indigenous communities sustainably shucked oysters for thousands of years
In estuaries around the world, centuries of overharvesting have caused oyster populations to plummet. The decline of these filter-feeding reef-builders damages the entire ecosystem. But new research by museum anthropologist Torben Rick reveals that humans were able to sustainably harvest oysters for millennia prior to colonial times. The team studied accumulations of oyster shells called middens — a few of which towered up to 30 feet into the sky — left by Indigenous communities in North America and Australia. In a study published in the journal Current Biology, Rick’s team concludes that these communities were able to consume billions of oysters without causing populations of these precious bivalves to crash. Tapping into some of their practices may improve current efforts to restore oysters in places like the Chesapeake Bay.
A mysterious bonebed was once a marine reptile maternity ward
Long before whales swam onto the scene, the ocean’s biggest behemoths were ichthyosaurs, a suite of marine reptiles that resembled souped-up dolphins. One of the largest ichthyosaurs known is Shonisaurus, a humpback whale-sized predator that terrorized late Triassic seas more than 225 million years ago. Bones from at least 37 Shonisaurus individuals have been found at Berlin-Ichthyosaur State Park in the middle of the Nevada desert. For decades, paleontologists have attempted to figure out why so many ichthyosaurs perished here. Some believed these marine reptiles were poisoned by toxic algal blooms while others posit they met their end during a mass stranding event.
Smithsonian paleontologist Nicholas Pyenson recently teamed up with several researchers, including former museum fellow Neil Kelley to reinterpret the iconic site. They collected samples of the surrounding rock to recreate the area’s ancient environment, sifted through museum collections for fossils from the site and partnered with the Smithsonian Digitization Program Office to digitally recreate the jumble of Shonisaurus bones still in the ground with 3D imaging. In a study published in the journal Current Biology, they concluded that the site was once an ichthyosaur birthing ground. Like modern whales, these marine reptiles returned to this location over generations to give birth. Instead of one cataclysmic disaster, the site’s bones accumulated over hundreds of thousands, or even millions, of years.
The secret to how mammal ancestors became warm-blooded is in their ear
One of the traits that make mammals so widespread is their warm-bloodedness. Unlike reptiles, who rely on the external temperature to keep them warm, mammals are able to maintain a near-constant body temperature, allowing them to conquer chilly climates.
How and when this game-changing trait evolved in the earliest reptile-like mammal ancestors has remained enigmatic. But a team including paleobiology research fellow Jacqueline Lungmus found a clue to this adaptation’s timeline hidden in the fossilized ear canals of early mammals and their kin. These canals contain a fluid called endolymph that aids balance and the viscosity, or runniness, of the fluid is impacted by an animal’s internal temperature. Because mammals maintain a high internal temperature, their ear canals have become narrower over time to help them stay balanced. In a study published in the journal Nature, the researchers concluded that warm-bloodedness evolved 233 million years ago during the Triassic alongside other mammalian features like whiskers and furs.
An ancient human’s meat-based diet gets a closer look
The appearance of Homo erectus two million years ago appears to be a turning point in human evolution. Unlike older early humans, Homo erectus sported a large brain and walked upright. It also appears to have had a taste for meat — eastern Africa is littered with fossil sites brimming with butchered animal bones from the time that Homo erectus was walking around.Scientists have long believed this fondness for flesh influenced Homo erectus’s brain size and proportions. But paleoanthropologist Briana Pobiner, of the museum’s Human Origins Program, recently took a closer look at several of these fossil sites and concluded that their influence is partially due to sampling bias. Paleoanthropologists have paid more attention to sites in this region, missing out on potentially older evidence of human carnivory in other areas. In a paper published in the journal Proceedings of the National Academy of Sciences, Pobiner and her team conclude that the human-like traits of Homo erectus are likely due to other factors beyond their protein-packed diets.
The largest dinosaurs avoided the cold
In recent years, fossil evidence has revealed that several dinosaurs, including some tyrannosaurs, were capable of surviving in chilly polar climates. One group of dinosaurs that did not make the trek poleward were sauropods, a class of long-necked, supersized herbivores that included giants like Diplodocus. In a study published in the journal Current Biology, museum paleontologist Matthew Carrano compared the sauropod fossil record with models of ancient climates to discover that these immense herbivores appeared confined to lower latitudes and were particularly diverse on southern continents. Here, hot and tropical habitats offered the optimum climate for thundering herds of sauropods to thrive.A guide for conserving biodiversity at the microscopic scale
Many researchers agree that the Earth is currently in the midst of its sixth mass extinction as animals like coral, bees, bats and amphibians disappear at alarming rates. To stem this biodiversity crisis, an international group of researchers including Smithsonian scientist Blake Ushijima recently teamed up to explore what methods can be adopted to protect ecosystems at their smallest scale — the microbiome. Microbiomes are communities of microbes like bacteria, fungi, algae and viruses that are found everywhere from coral reefs to the human gut. These complex communities help keep larger ecosystems healthy, which is why it is paramount to maintain microbiome diversity. In a paper published in the journal Nature Microbiology, Ushijima and his co-authors outline a framework for conserving these tiny, yet essential, biological communities.
Humans threaten to break a 66-million-year-old ecological rule
For mammals, size is all about diet. For 66 million years, the relationship between what a mammal eats and how big it is has resembled a ‘U’ — at the two ends of the spectrum are large herbivores, like mammoths and ground sloths, and large carnivores, like bears and saber-toothed cats. In between these two groups are smaller omnivores like rodents and insectivores like armadillos. This relationship has held firm since the extinction of the non-avian dinosaurs. But a new study published in Nature Ecology and Evolution featuring Smithsonian researchers Jonathan Lefcheck and Sara Lyons has uncovered evidence that humans are flattening this curve by driving large herbivores and carnivores to extinction. The disappearance of these massive mammals threatens to have an outsized impact on terrestrial ecosystems around the world.
Two newly discovered Amazonian fish are already swimming towards extinction
The Amazon River is brimming with aquatic life, including dolphins, crocodilians and more than 3,000 species of fish. In a recent study published in the Zoological Journal of the Linnean Society, museum ichthyologist Murilo Pastana and his team added two new fish species to the Amazon’s aquarium. Both species are roughly an inch-long and belong to a group of fish known as South American darters. One of the species, Poecilocharax callipterus, which sports striking red and orange fins, is only found in a single stream. Unfortunately, both species live in a region of the Brazilian frontier experiencing habitat loss due to logging. The researchers fear these two new fish are already at risk of extinction.
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