museum life science

WHERE DO MAMMALS COME FROM?

The Earth plays host to a remarkable variety of creatures all of which diverged from a single, unknown common ancestor. In the 540 million year history of complex life there have been repeated turnovers in dominant life forms, from The Age of Fishes during the Devonian to The Age of Reptiles during the Mesozoic which gave way to our current era in time, the Cenozoic, or otherwise known as The Age of Mammals. But where do mammals come from…?

Pelycosaurs…
The Pelycosaurs first appeared 306Ma and are the most basal synapsids. Synapsids are mammal-like reptiles; a distinguishable feature is their skull with only one post orbital fenestra, reptiles have two. The mammal-like reptiles show the earliest signs of evolution towards more mammal characteristics, Dimetrodon is a classic example. Dimetrodon had only a single temporal fenestra, this feature allowed for jaw muscle attachment to be further back providing a stronger bite force over a wider range of jaw movements, subsequently making Dimetrodon one of the most successful predators of its age.
Dimetrodon quite literally means “two sets of teeth” and this refers to its elongated incisors, this is the beginnings of the mammal feature known as heterodonty (differentiated teeth). Dimetrodon also exhibits deep ridges of the inner nasal cavity providing a larger surface area for the attachment of olfactory epithelium indicating a larger reliance of the sense of smell (something that will become more important in future mammal evolution).

Therapsids…
Therapsids appear around 275Ma and likely evolved from pelycosaurs or a similar sort of ancestor. They are still classed as synapsids but they even more mammal-like features than their ancestors. Therapsids have less of a sprawling gait than the pelycosaurs and other reptiles (although the herbivorous kind still retain a rather sprawling gait, this is a feature that is slow to disappear). Therapsids have an even larger temporal fenestra and more elongated incisors as the teeth continue to differentiate. The skull of therapsids is also beginning to change; mammals have a single jaw bone called the dentary, this is present in synapsids along with many other jaw bones such as the quadrate and articular, but as mammal evolution gets underway the dentary expands and the quadrate and articular reduce in size and become part of the middle ear bones. Some Therapsids were apex predators throughout the permian such as Gorgonops.

Cynodonts…
Cynodont fossils are some of the most important fossils in the mammals evolutionary record and we are classed as part of Cynodontia. They are dog-like creatures and appear around 260Ma, they were hugely successful and diversified rapidly. One of the best examples of cynodonts in mammal evolution is Thrinaxodon. The cynodonts exhibit even greater tooth differentiation and tooth occlusion (precise tooth contact of the upper and lower teeth, a feature unique to mammals). Tooth occlusion also suggests the cynodonts had controlled tooth replacement like mammals (mammals exhibit diphyodonty meaning two sets of teeth, the milk teeth and the adult teeth).
More importantly, cynodonts also show partial or complete secondary palates meaning they are able to swallow food and breathe at the same time, something reptiles cannot do. Many taxa also show absence of abdominal ribs allowing for the presence of a diaphragm which increased lung capacity. A diaphragm paired with the secondary palate and tooth occlusion suggests that cynodonts had a higher metabolism than other extant animals of the time. The cynodonts dentary continues to expand further back of the skull.
Some cynodont skulls have small indentations around the nasal region which may be indicative of nerve passages towards sensitive hairs, possibly whiskers, if so, cynodonts had hair. Thrinaxodon and others also have a larger brain size in comparison to the rest of the body than other animals as well as enlarged auditory and olfactory regions suggesting they were nocturnal.

The Permian extinction struck 250Ma due to extensive volcanism of the Siberian Traps leading to a runaway greenhouse effect. Between 80% and 96% of living species died out, including most of the cynodonts and the therapsids. Reasons why the reptiles battled through this extinction and rose to dominate is still debated but it may be due to the fact that reptiles can secrete nitrogenous waste as a uric paste whereas mammals must secrete is as a liquid. This allowed the reptiles to conserve water and see the extinction through.
Whilst most cynodont species perished, a few individuals made it through, they were mostly small, nocturnal burrowers capable of getting water from underground root nodules and tubers. However, the cynodonts would not rise to dominance again but their descendants would, although not for another 200 million years. They would spend the Mesozoic Era in the dinosaurs shadows, their evolution driven by a nocturnal lifestyle and the need for endothermy. The evolution of our ancestors was shaped by the dominance of the dinosaurs, when their reign ended 65 million years ago our true mammalian ancestors would quickly take over the niches left behind and become some of the most spectacular creatures the world has ever seen.

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Shelf Life episode 15 uncovers The Guts and Glory of Object Conservation. In the Museum’s Objects Conservation Laboratory, walrus intestines, birch bark, and reindeer hide are all in a day’s work for conservators trying to preserve Siberian anthropology collections for the future.

This is StarStuff. 

The cloudy, nebulousness of this vial are nanodiamonds, carbon molecules only a thousand atoms strong, bonded together. During the formation of our solar system a cloud of dust ballooned from the collapse of a massive molecular cloud and was circling around what would be our new, baby sun. These carbon atoms were trapped within larger molecules and compounds and became inclusions, embedded within meteorites which would become evidence of the earliest solids that condensed from the cooling of protoplanetary disks.

The Field Museum has part of the oldest known meteorite - the Allende meteorite - from which these carbon nanodiamonds were extracted through chemical processes developed by Philipp Heck, our Curator of Meteoritics. We know how old the solar system is by dating these inclusions from the Allende meteorite, giving us an estimate that our solar system is 4.567 billion years old. The carbon atoms I’m holding in the above photo are, in a sense, our greatest ancestor, and ultimately became the building blocks for all life on our planet. 

TL;DR I’m holding our greatest ancestor in the palm of my hand.

FROM THE OCEANS TO THE LAND

For millions of years life thrived in the abyssal plains and shallow seas, yet during this time the continental surface was barren and bleak, except for the few pioneering plants slowly creeping their way onto the land. As plant life got a foothold on the deserted surface rocks they began to transform the landscape waiting for animal life to follow. 

The transition from fish to tetrapod is one of the most important events in life’s history and we are lucky enough to have most of the puzzle on how it happened complete…

Eusthenopteron…
Eusthenopteron was a late member of a now extinct group of lobe-finned fishes and it existed during the Late Devonian, around 385 million years ago. The fishes pectoral and pelvic fins had a fleshy anterior part and very robust bones, the fore-fins exhibit a distinct radius, humerus and ulna and the pectoral fins have a femur, tibia and fibula showing that this 6 foot long fish was well on the way to developing primitive legs.

Pandericthys…
This was another lobe-finned fish from the late Devonian (378 million years ago). Panderichtys begins to show a more developed, longer humerus as well as primitive digits. Its tail is also more like the early tetrapod tails than the caudal fins of other lobe-finned fishes. They have also lost their intracranial joint to their skull (but it is still present), rather than it being external to the skull like in other lobe-finned fishes.

Tiktaalik…
Tiktaalik existed 375 million years ago and is still considered to be a lobe-finned fish although it shows even more tetrapod-like features than Panderichthys. The fleshy fins have primitive wrist bones and digits. They also have spiracles on top of their skull which may be possible indicators of primitive lungs. The humeral bones have large muscle scars suggesting that these appendages were highly mobile and the joints were capable of rotation, enabling Tiktaalik to have some sort of propulsion through the water. The eyes of Tiktaalik has moved further on top of a flatter skull and so it likely lived in a swampy, shallow water environment but was not yet completely terrestrial.

Acanthostega…
Acanthostega existed 365 million years ago and is the first to have distinct limbs, each of which has digits. However, the front legs were unable to bend forwards at the elbow and so it is unlikely that the animal was terrestrial as it was unable to move itself into weight-bearing positions.

Icthyostega…

Icthyostega was likely the first true tetrapod and existed between 365 and 360 million years ago. It has 4 robust limbs (with an unknown number of digits) and lungs which were still used in conjunction with gills. Icthyostega had wide overlapping ribs which likely helped to protect the lungs under its own weight without the buoyancy of water. Icthyostega has powerful limbs enabling it to haul itself onto the land but would still have spent much of its time in shallow, swampy water.

In this situation, "holding hands" is NOT necessarily a good thing.

Anonymous submitted:

I was working at a science museum while it was hosting a very popular traveling exhibit about human anatomy. I was selling audio guides at the entrance. A woman who had already passed my desk and headed into the exhibit came back around the corner to the audio guide station. She was cupping her hand in front of her, clearly holding something. 

She held out her hand to give me what she held. When I reached for whatever it was, she said “I just touched it very gently and these fell off." 

I looked down and I was holding the finger bones from a skeleton on display.

I lost the ability to speak for a moment. 

When I regained some words, I told her to PLEASE not touch anything else in the exhibit.  After she left (totally unconcerned about the situation) I got on the radio to call in the exhibits staff person. I must have sounded pretty flustered because he came running, along with the onsite traveling exhibition coordinator. Both were pretty flabbergasted when I handed them the bones. 

I now work at a different museum where no one hands me skeleton bits.

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My best friend from college was in Durham today, so we drove over to see her. We checked on the museum of life and science. It’s amazing! We only made it through the outside stuff, but we all had a great time.

WE DID IT. 

Thanks to more than 1,500 donors and even more who watched our video and shared our campaign, today I am thrilled to present our Indiegogo-created striped hyena diorama, now on display at The Field Museum. I’ve got lots and lots of feels - so here are the remarks I presented at our Hyena Homecoming event last night. My heart is bursting with joy. <3 

————–

Hi everyone. My name is Emily Graslie, and I’m the Field Museum’s Chief Curiosity Correspondent, and the host and writer of our educational YouTube channel, The Brain Scoop. Most of you know that already, but I haven’t yet become tired of saying it out loud. With the help of Jaap and the exhibitions department, our communications, marketing and fundraising teams, research and science staff, conservators, designers, supportive executives, the 50+ staff and over 1,500 donors from around the world, tonight we bring you the Field’s first-ever crowd-sourced project, and the first full-scale habitat diorama created here in over 6 decades.

I am ridiculously happy that you’re all here, and want to thank you for coming out tonight. Many of you traveled quite far to get here, and everyone in this room has waited for a long time for this special diorama.. depending on how you think of it, on the one hand it was a minimum of eight months in the making, and on the other hand, that figure is closer to eighty years. So, first and foremost, thank you for all of your hard work, patience, commitment, and the shared belief that Project Hyena Diorama was, in fact, a good idea.

That all being said, April 6th, 2015 - the day we launched Project Hyena Diorama on Indiegogo - was one of the most terrifying days of my life. The Brain Scoop was pretty much all fun and games up until that point. Because there aren’t a lot of comparable channels to The Brain Scoop, I calculate our program’s success with things like hand-drawn holiday cards from children, fan art, and letters from students recently inspired by our episodes to pursue new fields of study. But this was the first time we’ve taken a chance and gone out on a limb based off of a belief that those letters, comments, shares and retweets, and the thumbs-up on videos translate into a genuine and deep interest in museums and their roles in our lives. Project Hyena Diorama was a way to tangibly involve those digital supporters – including many of you – in a very real, very permanent thing.

None of us were 100% certain we would pull it off. But I imagine that same level of nervousness happened here when the Field decided to bring me on, and in doing so become pretty much the only institution with a full-time YouTuber on its staff. I’m told frequently that big ships turn slowly, and the Field Museum is one massive ship. I can’t emphasize enough how much faith my bosses and colleagues had to have had in me to even entertain this idea. When I say it couldn’t have happened without you, and the 1,400 other donors who couldn’t be here tonight, I genuinely mean it.  

So, fast forward six weeks from that terrifying launch date, and - spoiler alert - we did it! Then, people started asking me why I thought viewers and museum fans donated to the project. After all, hyenas aren’t the most charismatic creatures. So if you’re up for it, I’d love for some of you to let me know why you decided to help out and come here tonight, because honestly I’ve just been making up answers for you. “January is a great month to visit Chicago!” said nobody ever.

Your reasonings probably vary, but I’ll tell you why I was so compelled by this project idea. It’s the same reason why I’m so enamored with natural history museums in the first place. This diorama, and our museum collections, function to create and maintain a universally owned legacy.  

This project allowed us the opportunity to contribute to a history that is beyond any one individual, and spans almost a century of time. Today, we continue to consult Carl Akeley, a character who has been dead for ninety years, because he truly was a pioneer in this field, and his craftsmanship is still highly regarded. Our exhibits staff researchers and artists looked back many decades into the Field Museum’s history to learn more about artists and designers who came after Akeley, to make sure the techniques and materials used for the hyena diorama were in line with the wishes and intentions of those who began constructing the Hall of Asian Mammals back in the 1920s and 30s. And now, we’re able to use technologies available to us today to hone those practices. We contributed to improvements in conservation, we’ve utilized software that told us the exact star pattern in the sky for this moment in time, and we can rely on new knowledge about these animals that was unknown when the specimens were first collected.

Legacy is about the fact that our scientists care, in meticulous detail, about the exact shape and texture of the ball of dung that is being rolled by the tiny, mighty dung beetle in the front of this scene.

The very, very sad reality of why accuracy matters so much for dung balls and the beetles who roll them in museum dioramas is because there’s an exponentially growing threat of this scene not existing outside of Museums in another hundred years. What drives me to do the work that I do is knowing that I alone can’t stop that from happening, but I will do whatever I can to make sure we remember, share, and admire these moments in time, so generations from now children and adults can walk down this hall and become intrigued by what is naturally intriguing, and express curiosity for what is inherently curious. And your contributions to this project are the ultimate assurance that I am not alone in this idea of wanting to create compelling legacies that can be enjoyed and appreciated by hundreds of thousands of visitors to The Field Museum, and by just as many more who have gotten to know us through a twitter feed and YouTube interface. And that is certainly something to celebrate.

Thank you, from the bottom of my heart. 

Tardigrades—microscopic eight-legged animals that resemble plump piglets in puffer coats—have been charming and astonishing biologists since they were first discovered in the 1770s. Tardigrades are phenomenally successful organisms, having first appeared more than 600 million years ago. Though they’re common in moderate climes, terrestrial tardigrades are also one of the few animals that thrive in spots that are particularly inhospitable to life, such as Antarctica’s McMurdo Valleys, thought to be the driest and coldest desert on Earth.

To eke out a living in the mosses of Antarctica, and even in more mild places where their habitats are very vulnerable to sudden water loss, tardigrades have evolved a remarkable ability. When conditions turn life-threatening—whether from rapid drying, extreme dips in temperature, or spikes in salinity—they seem to defy death by imitating it. They temporarily wind down their metabolism in a reversible process called cryptobiosis—literally, hidden life.

There’s still much to be learned about the mechanisms by which tardigrades become cryptobiotic when faced with different stressors. The dramatic change they undergo in response to lack of water—anhydrobiosis, first described by Spallanzini in 1776—is still the best understood.

First, the animal curls into itself, tucking its eight limbs and head inside its body. It sheds more than 95 percent of the water in its body, shriveling into a blob, known as a tun for its resemblance to a beer barrel. In the process, the tardigrade produces a sugar that replaces the lost water, protecting internal structures from fatal damage. Metabolic processes dwindle to less than 0.01 percent of normal activity as the animal waits for conditions to improve. Just add water, and these “barrels” transform back into active “bears.”

Tardigrades star in the exhibition, Life at the Limits: Stories of Amazing Species, now open at the Museum. 

Tiger sketch, just for fun.

There’s an incredible life science museum near my house. Tons of great taxidermy. I have mixed feelings about the morbidity of the stuffed pieces, but I’m trying to make good use of them.

Pictured is a pair of platypus nests, collected by Australian naturalist Henry Burrell in the early 20th century. These nests are just two of more than 33 million specimens and artifacts that make up the Museum collection, a repository where discoveries are made all the time. The olinguito, a South American raccoon relative, spent nearly 90 years on the Museum’s shelves before being described as the new species. 

Learn the story in Episode 4 of Shelf Life: The Skull of the Olinguito


AMNH/D.Finnin

Before the days of Bill Gates and OS updates, the word “computer” was used (as far back as the 17th century) to describe a person who performs calculations. The latest episode of Shelf Life includes a segment about Henrietta Leavitt—an astronomer and human “computer” whose discoveries allowed researchers to determine cosmic distances.

Leavitt was one of a group of about 80 women, known as “the Harvard Computers,” who worked at the Harvard Observatory at the turn of the century. The Computers were hired by the Observatory’s director, Edward Charles Pickering, to help catalog and analyze thousands of early photographs of the night sky.

This assembly of scientifically-minded women has a somewhat apocryphal origin story: that Pickering—frustrated with his assistant’s sloppy cataloging—fired the male staffer with the words, “Even my maid could do a better job.” He did, in fact, then hire his maid Williamina Fleming as the first of the female computers. Fleming, who had been a teacher before becoming a maid, made several lasting contributions to astronomy, discovering the famed Horsehead Nebula and helping to develop a temperature-based classification system for stars.

The Computers worked six-day weeks and earned between 25 and 50 cents an hour.  Employed as technicians, their tasks included measuring the brightness of stars and analyzing spectra to determine the properties of celestial objects. Aside from their clerical bookkeeping, however, many of the women were fascinated with astronomy and made discoveries of great importance.

Annie Jump Cannon was hired by Pickering in 1896, but unlike some of her fellow Computers, she’d previously studied physics and astronomy at Wellesley and Radcliffe. Cannon classified hundreds of thousands of stars in her career and developed a standard stellar classification system that’s still in use today. She became the first woman elected as an officer to the American Astronomical Society and was the first woman to receive an honorary degree from the University of Oxford.

Today, Museum astrophysicist Ashley Pagnotta (featured in the latest Shelf Life episode visits the Harvard College Observatory at least once a year to look at glass plates of the night sky and revisit the data generated by the Harvard Computers. “I use the same plates that these women did,” says Pagnotta. “When I go through them, I come across ones that have their notations. That’s one of my favorite things about going to the plate stacks. These are women whom I’ve looked up to for a long time.”

This post was originally published on the Museum blog

In his book The Search for the Giant Squid, marine biologist and Museum Research Associate Richard Ellis speculates that even Greek myths of the many-armed Scylla and the Hydra, one of Hercules’s foes, could have been inspired by glimpses of giant squid.

Since enormous cephalopods, like the giant squid, usually keep to mid- to deep-water habitats, the most common way to see a giant squid would have been to spot a dead or dying squid that had floated to the surface. These animals’ bodies—long, thin, and utterly strange—may have helped to give life to legends of serpentine sea monsters. 

Read more on the Museum website

Scallops are built like clams and mussels, with shapely shells, soft, headless bodies and simple brains. Shellfish like these may not seem alert. But scallops see in all directions. Their mantle—the thin body part that secretes the shell—is fringed with up to 100 miniature eyes, each with its own tiny retina and lens. Scallops live on the seafloor, rather than buried in sand or attached to rocks. When their shells are open, they can monitor their surroundings at all times. 

Two rows of limpid blue eyes peer from the open shell of a sea scallop. Scallops have the most acute vision of any bivalve. Their multiple eyes sense light and movement, helping them guard against predators like starfish, sea urchins, and sea snails. A scallop can also see when the water is clouded with the microscopic algae and other particles it consumes. 

Meet more marvelous creatures in the exhibition, Life at the Limits, now open at the Museum. 

Some one has seen Jurassic Park a few too many times.

A volunteer came in to the reception desk at the science center I worked at in warning me that a lady was coming in with an odd donation, despite the fact that he had warned her that a) we were not a collecting institute, and b) she was wildly inaccurate about her “specimen." 

I agreed to talk to her, and a lady (who by all appearances, seemed the type who had a LOT of fun in the 1960s), came into the reception area. She was extremely excited and insisted that, while in her garden, she had uncovered the fossil of a of previously unknown TINY T-REX species.

I looked at this henceforth unknown “Tiny T-Rex” skeleton she had unearthed. 

It was a mouse skeleton.

I tried to explain this by pointing out that the bones were much too fresh to be fossils, and our part of the country had been under water during the Cretaceous period anyway…

But she wasn’t having any of it. I finally gave her a free pass so she could go show it to our Paleo Educator who hopefully would be seen as having more authority in these matters. 

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Open the drawers of a Museum collection, and oh the discoveries you’ll make!

Ninety years after it was collected, Mammal #66753 was finally recognized as a new species. This is the tale of the olinguito’s journey from obscurity to scientific treasure.