This Weekend at Museum of the Earth

Science on the Half Shell Opening Reception
Friday, September 24
6:30 p.m. to 8:30 p.m.
Tickets $10
Join us at the Museum of the Earth on Friday, September 24 to celebrate the opening of our newest exhibit, Science on the Half Shell: How and Why We Study Evolution. Come learn about all different kinds of bivalves - clams, scallops, oysters, mussels, and more - while snacking on raw fresh-shucked oysters and little neck clams provided by Maxie's Supper Club. In addition to the raw bar, sample some of Maxie's famous Jambalaya (vegetarian and non-vegetarian) and sip on wine from Atwater Estate Vineyards. Purchase your tickets online.


Science on the Half Shell Family Day
Saturday, September 25
11 a.m. to 3 p.m.
Come participate in a fun-filled day with activities for the whole family. We'll be celebrating our newest temporary exhibit, Science on the Half Shell: How and Why We Study Evolution. Included with Museum admission, free for Members.

A Sneak Peak...

 Assembling the Tree of Life at the Museum of the Earth with a new exhibition:
Science on the Half Shell: Exploring How and Why We Study Evolution

The Museum of the Earth will be opening its newest temporary exhibition, Science on the Half Shell: How and Why We Study Evolution, tomorrow -- September 24th, 2010.   This exhibition is made possible through a multimillion-dollar award from the National Science Foundation’s Assembling the Tree of Life Program to study the evolution of bivalves.  The Museum of the Earth, in conjunction with the Field Museum of Natural History and Harvard University, are the lead recipients of this grant.

Bivalves (clams, oysters, mussels, scallops, etc.) are a diverse and familiar group of mollusks with an old and well-preserved fossil record, important ecological roles in marine and freshwater ecosystems, and economic roles including fisheries, the ornament industry, and health sciences. With 20,000-30,000 living species, bivalves are the second largest class of living mollusks, which in turn form the second largest animal phylum and the largest in the sea. Despite the ubiquitousness of bivalves, past efforts to study and understand their evolution have been poorly coordinated. This project takes an in-depth look at bivalve anatomy, emphasizing gills, the stomach, shell ultrastructure, and sperm, and will sequence 10-12 selected molecules (genes) for the same set of approximately 300 species.

Dr. Paula Mikkelsen, PRI’s Associate Director for Science and one of the Principal Investigators on the NSF grant, explains “This exhibition gives us an opportunity to show visitors what evolutionary biologists do in the field and in the laboratory every day – using tools ranging from a simple sieve to a sophisticated CT scan – plus a little bit of why ordinary clams are such extraordinary animals.”

This exhibition emphasizes evolution and its many components (including diversity, taxonomy, biogeography, speciation) using bivalves – a group of organisms that is morphologically “simple,” familiar, and attractive, diverse enough to show examples of many different kinds of evolutionary processes, easy to obtain, and represented by an ample fossil record. After the exhibition’s run at the Museum of the Earth, it will travel around the country with stops scheduled at Harvard and the Field Museum in Chicago.

An evening opening reception will take place on September 24th, 2010 from 6:30PM-8:30PM.  Guests will have the opportunity to socialize with friends, meet the scientists, and be among the first to see the exhibition. The event will feature a raw bar and other delectables from Maxie’s Supper Club and wine from Atwater Estate Vineyards.  Tickets are $10 and can be purchased online at museumoftheearth.org or by calling 607.273.6623 x11. 

On September 25th, there will also be a Family Day celebration, where kids and their families can explore living and fossil bivalves and this new exciting exhibition.

Science on the Half Shell: How and Why We Study Evolution will be on display at the Museum of the Earth from September 24, 2010 through January 17, 2011.  Accompanying the exhibition will be an art exhibit entitled, Enduring Shells: Bivalves and Other Mollusks, a collection of 10 drawings of mollusks created by Groton, NY artist Marla Coppolino.

The National Science Foundation was awarded to Dr. Paula M. Mikkelsen of the Paleontological Research Institution (Ithaca, New York), Dr. Rüdiger Bieler of the Field Museum of Natural History (Chicago, Illinois), Dr. Gonzalo Giribet of the Museum of Comparative Zoology (Harvard University, Cambridge, Massachusetts), and twelve other international collaborators. A second NSF research grant to Dr. Scott Steppan at Florida State University (also involving Drs. Bieler and Mikkelsen) provided additional funding for the exhibition.

Science on the Half Shell: How and Why We Study Evolution is made possible with support from the National Science Foundation, M&T Bank, and Maxie's Supper Club.

Fossil of the Week

9/22 – Giant Clam

Our exhibition Science on the Half Shell: How and Why We Study Evolution opens at the Museum of the Earth this Friday, September 24. In recognition, this week’s “Fossil” of the Week is the living Giant Clam, Tridacna gigas.

With a weight reaching 270 kilograms (500 pounds) and a size of 1.2 meters (4 feet) across, Tridacna gigas is the largest living bivalve. Its average lifespan is more than one hundred years and one individual produced the largest pearl on record, weighing 7 kilograms (15.4 pounds) with a length of 23 centimeters (9 inches). These clams live in symbiosis with algae (zooxanthellae) that live in the colorful body tissues lining the upward-facing zig-zag margin of the clam. This exposes the algal cells to the light that they need for photosynthesis; this need also limits this species to shallow-water reef habitats. The zooxanthellae provide a major portion of the clam’s food (the clam also filter feeds) and also recycle its waste products.

Many myths surround Tridacna, which lives in the shallow waters of the southern Pacific and Indian oceans. Its height of popularity was arguably as a man-eating killer clam trapping unsuspecting divers, stories that persist today in cartoons and B-movies that portray drowning divers in the stranglehold of the vicious clam. But despite its gruesome reputation, nobody has ever been attacked by a Giant Clam; it lives solidly embedded in the reef and because of its bulk, closes its valves very, very slowly, allowing almost any potential victim ample time to escape its grasp. In medieval times, Tridacna shells were used in churches as holy water stoups and baptisteries. Tribes in the Indo-Pacific region made ceremonial figurines out of these clams, and Solomon Islanders used pieces of its shell as money and symbols of wealth. Today, the Chinese and Japanese enjoy the meat of Tridacna as a delicacy, and their large shells are still much-sought curios. The continuous popularity of the Giant Clam has lead to intense overharvesting and has put Tridacna on the list of worldwide endangered species.

The fossil record of Tridacna is only poorly preserved, but it can definitely be traced back to the Miocene Epoch (Quaternary). The subfamily Tridacninae (in the family of heart-cockles, Cardiidae) originated in the Tethys Sea – in the middle of modern-day Europe – but is now restricted to the Indo-Pacific region. The Tridacna gigas specimen pictured here (PRI 50338) was collected in 1946 from the lagoon at Bikini Atoll, eight years before the famous nuclear tests were conducted there. The name Tridacna gigas is attributed to Linnaeus, 1758 – this is the 10th edition of Systema Naturae, the first work to use binomial nomenclature (the two-part names, genus and species, for each kind of animal and plant).

Text by Judith Nagel-Myers (reprinted from “Fossil Focus” in American Paleontologist, Fall 2007)

Fossil of the Week

9/16 – “Pre-Scallop”

Scallops – today members of the bivalve family Pectinidae – have been alive on Earth since the early Triassic Period, approximately 240 million years ago. They are characterized by “ears” (called auricles) on the shell and a notch below one of them through which a set of elastic threads (a byssus) emerge to help hold the scallop, during at least its juvenile life, to the sea bottom. At the edge of the byssal notch in most scallops is a comb-like set of spines (the ctenolium) that separate and support the byssal threads. The direct ancestors of scallops were scallop-like bivalves of the family Entoliidae, which lived during the Paleozoic and Mesozoic Eras (400-65 million years ago). Entoliids had auricles and a byssal notch only as juveniles, but they did not have a ctenolium. The ctenolium – a defining feature of the modern family Pectinidae – is a feature that evolved within the scallop lineage.

This Fossil of the Week is Entolium aviculatum (Swallow, 1858) (PRI 14077, 2.25 cm in diameter), from the Carboniferous Period (approximately 330 million years ago) of Henry County, Missouri. This specimen is a “steinkern” or internal cast – a mold of the inside of the shell made when the mud inside the shell turned to rock, and the pieces of shell fell away; the inside of the other valve shows on the other side of this fossil. The auricles of the specimen are to the right and left of the umbo (the oldest part of the bivalve, including the larval shell) at top center. Entolium aviculatum was originally described in the genus Pecten in the scallop family Pectinidae. The genus Entolium was distinguished by F. B. Meek in 1865 (still in the scallop family Pectinidae) as different from most scallops in having indistinct auricles and no notch for the byssus (these features are now known to be present and most obvious only in juvenile entoliids). The family Entoliidae was not separated from Pectinidae until 1960 by the Russian paleontologist I. A. Korobkov. This is a good example of the complicated string of events that often ensues in naming and distinguishing species, especially in paleontology, in which the number of specimens and/or the quality of specimens may limit our knowledge (at least for a time) about the features that define families, genera, and species.

George Clinton Swallow (1817-1899) led an interesting and varied life. He was a native of Maine, was educated at Bowdoin College, and was Missouri State Geologist when he described this species. He held professorships and state geologist positions in both Missouri and Kansas, but later left paleontology to become a medical doctor. He was teaching at a medical school in Missouri when he had a dispute with the President and was dismissed. He then became a newspaper editor and state inspector of mines in Montana. In 1858, Fielding Bradford Meek (1817-1876; who described the genus Entolium) accused him of unfairly taking credit for being the first to recognize Permian fossils in North America, which ignited a long controversy over the Permian Period in Kansas. Swallow was also accused of disloyalty during the Civil War, and was jailed twice in 1862.

Text by Paula Mikkelsen

Natural History @ Noon

The School of Rock

(Image courtesy www.joideresolution.org)

Don Duggan-Haas, Education Research Associate here at PRI and its Museum of the Earth is currently aboard the JOIDES Resolution for the School of Rock 2010, Deep Earth Academy's signature professional development program for educators.

During School of Rock, participants will spend 12-hour days working along-side a dynamite team of instructors and crew who will guide them in their own exploration of cores, CORKS, and logging data from the Cascadia region and beyond. Using the high-tech laboratories on board, and their own observational and problem-solving skills, they will be challenged to integrate diverse sets of data from deep in the ocean floor to recreate the geology and history of the Earth. Much of their experience will also involve developing programs and products that focus on their experience, the JOIDES Resolution, and scientific ocean drilling.

Follow along as Don and his other shipamates blog about their experience: School of Rock
Don's latest post: The JR isn't just big. It's a big deal.

Fossil of the Week

9/8 – Flowering Plants of the Green River Formation

If you’ve ever heard of the Green River Formation – an Eocene Lagerstätte found in western Colorado, southwestern Wyoming, and eastern Utah – your first thought is probably about a spectacular fossil fish. Although less familiar, Green River fossil plants are equally spectacular. The PRI collections contain a large number of fossil vertebrates, insects, and plants from the Green River.

The Green River Formation* beds represent about six million years of freshwater lake sedimentation during the Eocene Epoch approximately 48 million years ago. Many of the sediments are so fine grained that they have preserved soft parts not usually found in fossils, including the scales of fish, and the delicate leaves and flowers of trees that fell into the lakes. There are even known cases of insects preserved in the act of eating some of the leaves. In addition to angiosperms (flowering plants like those pictured here), the Green River flora includes fossils of freshwater algae, and terrestrial plants such as ferns, conifers, and horsetails.

Although interesting from a taxonomic and evolutionary point of view, the plant fossils found in the Green River Formation are also particularly useful as climate indicators. They show that despite being centered at about the same latitude as they are today, the Eocene Green River plants were living in the moist subtropics.

In this photo are (clockwise from the left) a tropical hardwood stump, Yellow Point Playa, Wyoming (PRI 2007, Acc 1484, K22079); Schinoxylon Pepper Tree log, Blue Forest, Wyoming (PRI 1999, Acc 1104, K16976); Styrax transversa twig, Garfield County, Colorado (PRI 1979, Acc 722, K6312); Celastrus winchesteri, Staff Tree leaf, Garfield County, Colorado (PRI 1979, Acc 722, K6318); and (at center) a flower, Garfield County, Colorado (PRI 1979, Acc 722, K6188).

Of course, the Green River Formation shows just one way in which fossil plants can be preserved and there are many others. In the Museum of the Earth permanent exhibits, you can see plants from other locations and time periods, including some microscopic flowers that have been burnt and preserved as charcoal.

Text by Ursula Smith (reprinted from “Fossil Focus” in American Paleontologist, Fall 2009)

*For more about the Green River Formation, see Fossils of the Week 10/8/09 - Flower and 7/9/09 - Sycamore Leaf.

This Weekend at Museum of the Earth...

Fossil of the Week

9/1 – Blastoids

Blastoids are extinct echinoderms (related to living seastars, sea urchins, sea cucumbers, and crinoids) that are quite common fossils. Although not as well known as crinoids*, they share many similarities in life style and history. Blastoids appeared during the Ordovician Period and disappeared during the end-Permian extinction, having reached their peak during the Lower Carboniferous (approx. 350 million years ago). Like other echinoderms, they have radial symmetry, which is particularly obvious in the specimen pictured here on the right in which five ridges radiate away from the mouth.

The part of the organism that is pictured here is called the “theca” and is made up of a series of tightly interlocking calcium carbonate plates. This makes the theca quite robust, so blastoids have a good fossil record and are common as fossils in rocks of the right age and environment. Blastoids are often described as looking like fossilized hickory nuts, but the thecae vary in shape and size from fairly globular, like these specimens – Pentremites godani from the Mississippian of the Paint Creek Formation, St. Clair County, Illinois, PRI Acc. #1493 – to more elongated or much more angular.

Like crinoids, living blastoids had a stalk that was attached to the ocean floor by a holdfast. The stalk held the theca above the sediment, allowing the organism to feed. The stalks were not as tough as the thecae, and they fell apart more easily after death, so fossilized thecae are usually found without stalks. You can see in the specimen on the left where the stalk would have been attached to the theca at the bottom. Blastoids fed on plankton that they filtered from the water using delicate structures called “brachioles” that are rarely preserved. The brachioles radiated from the five “ambulacra” that are clearly visible on these specimens – they form the ridges that radiate away from the top of the specimen on the right and can be seen to truncate before reaching the bottom end of the theca on the left.

Text by Ursula Smith (reprinted from “Fossil Focus” in American Paleontologist, Spring 2010)

*See Fossil of the Week 4/29/09 - Crinoids.