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Archive for the ‘Invertebrates’ Category.

Understanding the evolutionary history of the cassiduloid echinoids

Photographs of Rhyncholampas gouldii (Bouve) (Cassidulidae) in aboral, oral and posterior view (from left to right).

Figure 1: Photographs of Rhyncholampas gouldii (Bouve) (Cassidulidae) in aboral, oral and posterior view (from left to right).

It is widely recognized that major groups evolve at different rates, in their own evolutionary trajectories. Some evolve fast and are very diversified while others evolve slowly and may never experience an explosion of diversity throughout their trajectory. One of my research interests is understanding the pace of morphological evolution through time, and the organisms selected to investigate this topic are the irregular echinoids.

Commonly known irregular echinoids include the sand dollars (clypeasteroids) and the heart urchins (spatangoids). They are called “irregular” because they evolved morphological innovations that depart from the “regular and pentaradial symmetric” type, seen in the sea urchins. Most of these innovations evolved convergently in different groups and are mostly adapted for their infaunal (i.e., burrowing) life style. For instance, irregular echinoids usually have a flattened test with thin spines that are more adapted for burrowing. They also evolved petals with specialized tube feet for breathing, their anus moved away from the apical disk possibly to avoid waste released near the petals, and they lost the Aristotle’s Lantern as adults and feed on the detritus in the sediment. Finally, irregular urchins have an anterior-posterior polarity and are said to have a secondary bilateral symmetry (the larvae has primary bilateral symmetry). Irregular echinoids evolved during the Mesozoic Marine Revolution and these morphological modifications are just a small part of their interesting evolutionary history! In addition, they live worldwide, their fossil record is excellent, and the major groups display very contrasting evolutionary histories.

Figure 2: Drawings of cassiduloid structures (on the left, the mouth and oral plates and phyllopores [i.e., pores where the tube feet specialized for feeding are found]; in the right, the oral ambulacrum II).

Figure 2: Drawings of cassiduloid structures (on the left, the mouth and oral plates and phyllopores [i.e., pores where the tube feet specialized for feeding are found]; in the right, the oral ambulacrum II).

Besides the sand dollars and heart urchins, there are three other groups of extant irregular echinoids: the holectypoids, echinoneoids and cassiduloids. One of the reasons you have probably never heard about them is that they are rare. My research focuses on the cassiduloids (Figure 1; some known as lamp urchins). Cassiduloids probably originated in the Cretaceous and reached a peak of diversity in the Eocene, when they composed about 40% of all echinoid genera. After the Eocene, their diversity declined sharply and today only about 30 species are known. Although their fossil record is very species rich, the cassiduloid morphology appears to be quite constrained. Few novelties evolved throughout their long evolutionary trajectory (as opposed to the heart urchins), and the species found today are mostly endemic and restricted to certain kinds of environments (e.g., mostly warm waters and with coarse grain sediments).

The classification of the cassiduloids is very controversial, and it has been shown that they may not compose a monophyletic group. Therefore, the first step of my research is reconstructing a time-calibrated phylogeny of the cassiduloid echinoids that will allow me not only test the relationship within the group but also to understand how the major cassiduloid groups relate to the other irregular echinoids. In addition, a phylogeny will allow me study the evolution of major innovations within the group, their rate of morphological change, and their patterns of biogeographic distribution through time. Because of the rarity and poor preservation of the cassiduloids in museum collections, I am focusing on the morphological data. Most of the characters analyzed focus on the plate patterns of the test, which can be seen in well preserved fossils, and I am also obtaining micro-computerized-tomography (i.e., 3D) images of extant specimens at the Lawrence National Berkeley Laboratory to find novel characters that are difficult to see with stereo-microscopes (Figure 2).

Many of the specimens included in my analyses are deposited at the UCMP and at the California Academy of Sciences. However, most of the extant cassiduloids are very rare and restricted to one or two scientific collections; and some are known only for their type specimens. To analyze such taxa I often have to visit these collections. After analyzing the specimens deposited in the Bay area museums, last summer I started exploring specimens deposited elsewhere.

Figure 3: Photographs of the Australian Museum building depicting a T-rex (head and tail can be seen coming out of the windows), of my Australian favorite terrestrial animals — the rainbow lorikeet and a kangaroo, and a record of my first time on the West Pacific ocean.

Figure 3: Photographs of the Australian Museum building depicting a T-rex (head and tail can be seen coming out of the windows), of my Australian favorite terrestrial animals — the rainbow lorikeet and a kangaroo, and a record of my first time on the West Pacific ocean.

My first stop was Australia (Figures 3–4). The Australian Museum in Sydney and the Melbourne Museum were chosen not because of the diversity of cassiduloids present but by the uniqueness of the species found there, both in the invertebrate and paleontological collections. One of advantages of visiting collections instead of asking for loans is the surprises we often find. For instance, I found a misidentified specimen in the Australian Museum whose species was known only by its two co-types. This specimen not only provided me with more information on the morphological variation of this species but also increased its known geographic range. I also had great surprises on the Melbourne Museum, where I could analyze two specimens that they had recently obtained and therefore were not present in their database. Besides analyzing cassiduloid species I had never seen before, I also met Frank Holmes, an amateur paleontologist who works in the Melbourne Museum and shares my passion for the cassiduloids. Frank has described cassiduloid species and we had great discussions over an undescribed Paleocene cassiduloid he is working on!

Figure 4: Photograph of the Melbourne Museum building (top left), of the Queen Victoria Market (a “must go” place in Melbourne according to the natives; bottom left), and of me and Frank Holmes in the paleontological collection (image on the table is of the new Paleocene cassiduloid) (right).

Figure 4: Photograph of the Melbourne Museum building (top left), of the Queen Victoria Market (a “must go” place in Melbourne according to the natives; bottom left), and of me and Frank Holmes in the paleontological collection (image on the table is of the new Paleocene cassiduloid) (right).

My next and final stop was the Smithsonian Institution National Museum of Natural History (NMNH) in Washington D.C. (Figure 5). Visiting their echinoderm collection was one of my dreams as an undergrad, not only because this collection houses the great majority of specimens I have always needed to analyze, but also because of the great researchers who have worked there, such as Theodore Mortensen, Elisabeth Deichmman, and Porter Kier. Their echinoderm collection is divided into three collections: the dry collection and the paleontological collection are housed in the main building in Washington D.C., and the wet collection is housed at their Museum Support Center in Suitland, Maryland (Figure 5). So I often travelled back and forth between these collections and focusing on the cassiduloid was not hard at all. There were just so many of them!!!

Figure 5: Photograph of the NMNH building (top left), of my workstation at the Museum Center in Suitland (bottom left), and of myself with the oversized echinoderms in the wet collection (right).

Figure 5: Photograph of the NMNH building (top left), of my workstation at the Museum Center in Suitland (bottom left), and of myself with the oversized echinoderms in the wet collection (right).

Figure 6: Book of the Springer room visitors; in detail, a record of the visit of the UCMP Director Charles Marshall in 1989 to analyze clypeasteroid echinoids (i.e., sand dollars)!!

Figure 6: Book of the Springer room visitors; in detail, a record of the visit of the UCMP Director Charles Marshall in 1989 to analyze clypeasteroid echinoids (i.e., sand dollars)!!

The NMNH echinoderm paleontological collection in particular surprised me for having its own room! The Springer room is dedicated to Frank Springer, an amateur paleontologist who donated a significant  echinoderm specimens (most of which are crinoids, Frank Springer’s favorites) and literature to the NMNH. The preservation of many fossils in the Springer room is superb and captures a great level of detail. The cassiduloid collection, for instance, is very diverse and is composed of fossil specimens from all over the world. This abundance is probably a result of Porter Kier’s work on the “Revision of the Cassiduloid Echinoids”. For most of the species, I could even choose five or more of its best specimens, a privilege I have never had in any other collection.

The Springer room also has one of the best libraries on echinoderm paleontology in the country, together with Porter Kier’s jacket, and a book of signatures which has recorded all history of visits in the room. Among these, I found the signature of the UCMP director Charles Marshall (Figure 6)!

At the end of my journey, I analyzed 47 cassiduloid species (eight extant and 39 fossils; about 150 specimens, including 13 type specimens). All this data was integrated into a morphological matrix, and the phylogenetic analyzes will be performed when I analyze all specimens chosen.

Cryptic caves and paleoecology of crustaceans in Cenozoic coral reefs

Just some months ago on a Saturday in July, I had the pleasure of snorkeling above the only coral reefs in the continental Unites States. These reefs in southern Florida still harbor many species of corals, fish, and other animals including crustaceans such as crabs, shrimps, and lobsters. These decapods are difficult to spot while snorkeling, but that does not mean they are not there. Their usually small size in this landscape of incredibly variable topography ensure they are able to hide effectively from predators. As for many other animals, coral reefs are a hotspot for decapod biodiversity. This was by no means different in the distant past. The rapid diversification of crabs and squat lobsters in sponge and shallow-water coral reefs during Late Jurassic is one of the best examples. When many reefs vanished in the earliest Cretaceous so did many of these crustaceans, highlighting the need to protect corals and, in doing so, also the associated, often cryptic animals.

One example of these cryptic animals are crabs from the Cryptochiridae family. Today, over 50 species are known of these tiny animals that have a carapace of less than a centimeter long. They do not hide in the rubble or between coral branches, but they create their own homes within the corals. Their home is either a true gall or a tunnel that is either circular/oval or crescentic in cross-section. Despite their high biodiversity, no convincing cryptochirid fossils were known until very recently.

Figure 1 white v2 small

The modern cryptochirid crab Troglocarcinus corallicola sitting snugly in a crescentic home in the coral Manicina areolata. Scale bar width: 50 mm for a, 5.0 mm for b. Source: Klompmaker, Portell & Van der Meij, 2016, Scientific Reports

Earlier this year, an open access article together with Roger Portell and Sancia van der Meij was published showing superbly preserved crescentic-shaped holes in Plio- and Pleistocene corals from Florida and Cuba. No animals other than cryptochirids create such holes so the culprit of this trace fossil was easy to identify. Unfortunately, no crabs were found inside the holes because these relatively soft and tiny crabs do not preserve well. Such crescentic holes should be present in more fossil corals all over the world. Why? Cryptic crabs that make such holes are found in corals in nearly all (sub)tropical regions of the world today. Additional evidence would help tremendously in constraining the antiquity of this family and with getting a better sense about their past biodiversity. So check out your fossil corals at home or in a museum nearby! Some places in the world expose fossil coral reefs as a good third alternative.

Figure x jpg

Pleistocene corals from Florida: Solenastrea bournoni (a, b) and Solenastrea hyades (c˗e) with close-ups of crescentic cryptochirid holes. Photo d shows the holotype of the trace fossil named after this particular shape: Galacticus duerri. The genus name is derived from Battlestar Galactica because of the similar cross-sectional shape of this battleship to these crescentic holes. Scale bar width = 50 mm for complete corals; 10 mm for close-ups. Source: Klompmaker, Portell & Van der Meij, 2016, Scientific Reports

That's exactly what I did in the summer of 2014, but for different reasons. I was lucky to receive funds from the Paleontological Society (Arthur James Boucot Research Grant) and a COCARDE Workshop Grant (European Science Foundation) to travel to Denmark to a very special fossil coral reef in the famous Faxe Quarry. This quarry is accessible to everybody and it certainly is a great place to visit when you are in Denmark as is the Geomuseum Faxe right next to it! My Danish colleagues Bodil Lauridsen and Sten Jakobsen helped to find the right places for collecting. The exposed coral and bryozoan mounds were living at 200-400 m depth in dim light conditions in the earliest Cenozoic (~63 million years ago). Such deep-water coral reefs can still be found all over the world up to depths of 1000+ meters by the way.


The Faxe Quarry at dusk after a long field day.


Author (right) with colleague Sten Jakobsen (left)

This complex reef at Faxe also contains decapods, primarily crabs and squat lobsters. After more than a century of collecting, as many as 25 species are known. That’s a lot right? However, well-sampled, shallow-water fossil coral reefs from elsewhere in Europe contain even more decapods.  The Cretaceous-Paleogene extinction event that wiped out the non-avian dinosaurs, ammonites, and severely affected many other groups has apparently nothing to do with the lower decapod diversity at Faxe. Our analyses show that decapod diversity is not affected by this event. Instead, less food and perhaps fewer hiding places have contributed to this lower diversity. A comparatively low decapod diversity is also seen in today’s deep-water coral reefs.

These critters may differ also in body and eye size compared to their shallow-water friends in corals reefs. The crabs at Faxe tend to be larger for half of the analyses, whereas other results show no difference. Some ideas about the reasons include a lower number of predators, a delayed maturity, and an increased life span of these crustaceans in deeper, colder waters. Quite spectacular evidence was found when we compared the eye socket size (true eyes are not preserved) for crabs of the same size and genus from Faxe to those from a shallow-water reef. While initial results did not seem to show much, a closer look at the data and additional measurements did show a distinct difference. The eye sockets of the crabs at Faxe are larger than those from a shallow-water reef! Thus, these crabs evolved larger eyes to see better in the dim light conditions in Faxe ~63 million years ago.


Leftover rocks from a number of days of field work at one of the sites in the Faxe Quarry.

Some crabs can be readily seen in the wall of the quarry. Here an example of a partially exposed carapace of Dromiopsis rugosus.

Some crabs can be readily seen in the wall of the quarry. Here an example of a partially exposed carapace of Dromiopsis rugosus.


Carapaces of crabs and some squat lobsters (c, d) from the Faxe Quarry in Denmark and some crabs from Spain (g, h). a. Dromiopsis rugosus; b, Dromiopsis elegans; c, Protomunida munidoides; d, Galathea strigifera; e & f, Caloxanthus ornatus; g & h, Caloxanthus paraornatus. The eye socket height of many specimens of the two species of Caloxanthus was compared. Scale bar width: 5.0 mm for a & b; 2.0 mm for rest. Source: Klompmaker, Jakobsen & Lauridsen, 2016, BMC Evolutionary Biology (open access)

The incredible biodiversity of fossil decapod crustaceans with ~3500 known species, many of them known from reefs, still results in the description of tens of new taxa each year by professionals and avocational paleontologists, often during collaborative efforts. With such data becoming more and more available, studies on diversity and paleoecology have become more common in recent years. The collection of the UCMP also does hold many, yet to be studied fossil decapods. Research on this exciting group of crustaceans continues!

Air-breathing snails, old and new

The UC Museum of Paleontology (UCMP) is home to more than five million invertebrate fossil specimens, a majority of them being marine in origin. While rehousing the US Geological Survey’s Menlo Park collections, I came across specimens of Actinella, a genus of terrestrial gastropod. The earliest known air-breathing gastropods in the fossil record appeared during the Carboniferous Period, Carboniferous being a reference to the abundant coal deposits formed at this time, 359 to 299 million years ago.

Actinella fossils

Actinella fossils from the US Geological Survey collection.

The name Actinella was established by the British naturalist Richard Thomas Lowe. While serving as a clergyman in the Madeira Islands — a Portuguese archipelago in the North Atlantic Ocean — Lowe collected, studied, identified and named many different snail genera and subspecies between the 1830s and 1850s. Lowe’s work is still cited today and used in the identification of Actinella fossils. In 1892, the Scottish malacologist Robert Boog Watson described specimens of Actinella in the Journal of Conchology. Thirty years later, Watson’s work with Actinella was referred to and further expanded upon by then University of Colorado, Boulder, Professor T.D.A. Cockerell in a 1922 edition of the journal Nature.

Terrestrial snails evolved from marine snails, but some modern relatives, such as Ellobium aurismidae, the Midas ear snail, have characteristics of both. Certain parts of the world have terrestrial snails that prefer wet habitats, like Carychium minimum, the herald thorn snail. Other snail species, such as Myosotella myosotis, the mouse ear snail, have adapted to live near water with high salinity.

Air-breathing snails

From left to right are the air-breathing terrestrial snails Ellobium aurismidae, Myosotella myosotis, and Carychium minimum.

Studies of living specimens of Actinella and other gastropods continue to generate interesting information. For example, in a 2008 Nature article, UC Berkeley Professor Nipam Patel and UC Berkeley postdoctoral fellow Cristina Grande discovered that snails use the same genes as humans do for right-left determination of internal and external structures. With continuing investigations into gastropods, both extinct and living, marine and terrestrial, fossils from UCMP’s USGS Menlo Park invertebrate collection just might lead to another discovery!


Actinella photo by the UCMP Invertebrate Collection crew. Ellobium photo © 2012 Femorale (CC BY-NC 3.0); image has been modified. Myosotella photo by Malcolm Storey (CC BY-NC-SA 3.0); image has been cropped. Carychium photo by H. Zell (CC BY-SA 3.0); image has been modified.

Flash! Grad student discovers how Ctenoides ales, the “disco clam,” flashes

Back in 2010, while diving in Indonesia, Lindsey Dougherty first witnessed the flashing behavior of the so-called “electric clam” or “disco clam,” Ctenoides ales. She decided then and there that the focus of her Ph.D. would be the study of these fascinating bivalve mollusks.

Disco clam flashing

Ctenoides ales caught in the act of flashing. In the photo, it's the silvery white band along the lip of the mantle. Photo by Lindsey Dougherty.

Now, four years later, Dougherty reports in the British Journal of the Royal Society Interface just how the flashing works. A nice description of the mechanism and a video showing the flashing behavior is provided in Robert Sanders’ article on UC Berkeley’s News Center website. Also see The Royal Society’s news blurb (with more video footage) about the study, listen to Lindsey describe her research in a New York Times Science Times podcast on iTunes, or check out this ABC News video that aired on July 23.

Lindsey on Cal Day

Lindsey Dougherty describes her work with Ctenoides ales to a Cal Day audience. Cal Day is the annual campus-wide open house that takes place every April. Photo by Jenny Hofmeister.

Dougherty is now looking into the reasons for the flashing behavior. Perhaps it attracts prey or serves as a warning to potential predators; or maybe it’s a signal to juveniles of its own species that this is a good substrate on which to settle. We’ll have to wait and see what Dougherty finds out!

Here are some of the other news outlets and organizations that picked up the disco clam story:

Encounters in the field: UCMP and the US Geological Survey

Buchia specimens

Buchia crassicollis specimens collected by J.S. Diller in 1899. Photo by Erica Clites.

Hundreds of specimens from the former USGS Menlo Park Collection, now housed in the UC Museum of Paleontology, were collected in the pioneering days of geological and paleontological exploration of California. This includes fossils collected by Charles A. White, Timothy W. Stanton, Joseph S. Diller and other legendary figures at the US Geological Survey. The newly founded Department of Paleontology at UC Berkeley also led numerous expeditions and excavations of vertebrates in California in the early 1900s; John C. Merriam and his crews discovered two hundred separate remains of Triassic reptiles in the Hosselkus Limestone, exposed in Plumas and Shasta Counties.1

In the summer of 1902, US Geological Survey and UC Berkeley paleontology crews had a chance meeting in the field near Redding. Along with Merriam, the Berkeley crew included preparator Eustace Furlong, as well as museum benefactress Annie Alexander and her traveling companion, Katherine Jones. Jones' diary recorded Alexander's encounter with Joseph Diller of the US Geological Survey while washing her hair in a stream. Diller asked "all sorts of leading questions as to the plans of our party and in fact knew our movements as well as we did." Alexander "gave as evasive answers as possible"1, not wanting Diller to co-opt their discoveries. Diller spent his career in the Pacific Northwest, and although not a paleontologist, he collected hundreds of fossils for the US Geological Survey. Despite the suspicion surrounding their initial meeting, Diller later referred Merriam to exposures of the Hosselkus Limestone in Cow Creek, where in 1910, Merriam and his crew discovered the skull and partial skeleton of the ichthyosaur, Shastasaurus.

Partial Shastasaurus skull

Partial skull of Shastasaurus pacificus (UCMP 9017) collected by John C. Merriam from the Late Triassic of California. Figure by Sander et al. (CC BY 3.0).2

Working closely with the USGS and associated UCMP collections, it is clear that UCMP and US Geological Survey staff visited many of the same places. I enjoyed reading this confirmation of such encounters. It seems fitting that the fossils collected by these two storied institutions are now reunited in the UC Museum of Paleontology.

1 Hilton, R.P. 2003. Dinosaurs and other Mesozoic Reptiles from California. University of California Press. 356 pp.

2 Sander, P.M., X. Chen, L. Cheng, and X. Wang. Short-snouted toothless ichthyosaur from China suggests Late Triassic diversification of suction feeding ichthyosaurs. PLoS ONE 6(5):e19480.

Reports from Regatta: T.W. Stanton, prominent contributor to the USGS Invertebrate Collection

In the orphaned U.S. Geological Survey’s (USGS) Menlo Park Invertebrate Collection, now housed in the UC Museum of Paleontology’s off-campus collections space in the Regatta Building, the work of prominent USGS collectors stands out. One of these dedicated and proficient invertebrate paleontologists was Timothy William Stanton, who amassed collections from over 100 localities, authored monographic research papers, and wrote more than 600 technical reports evaluating the age of collected specimens.

Stanton was born on September 21, 1860, in Monroe Country, Illinois. Early in his life, Stanton moved to Boulder, Colorado, where he received his Bachelor of Science and Master of Science from the University of Colorado. Stanton continued his graduate education in biology and geology at John Hopkins University and received a doctoral degree in those disciplines in 1897 from George Washington University.

Stanton’s name is encountered most often in association with Cretaceous invertebrates. His affinity for Cretaceous invertebrates developed when he lived in Boulder, surrounded by fossil-rich sediments of Cretaceous age. Stanton incorporated his research interests into his professional life when he was hired at the USGS and worked as an apprentice to Charles Abiathar White in the Cretaceous invertebrate collection. Starting in 1889, Stanton slowly made his way up the USGS ladder; he succeeded White as the head of the Cretaceous invertebrate collection, became the geologist in charge of the Paleontology and Stratigraphy branch, and in 1932, he became chief geologist of the USGS. Additionally, Stanton served as the president of the Geological Society of America and president of The Paleontological Society.


Bivalve specimens collected by Stanton in the Santa Susana Mountain Range, just north of Los Angeles. These specimens were collected during October of 1900, and constitute a small sample of Stanton’s fieldwork along the Pacific Coast. USGS Locality Number 2251.

During his time at the Survey — that spanned over 46 years — Stanton maintained field research in Texas, Colorado, the Gulf Coastal Plain, and the Pacific Coast. While working in Colorado, Stanton produced a comprehensive description of Cretaceous fauna in a monograph entitled The Colorado Formation and Its Invertebrate Fauna. The work is still valued as a remarkable text.

Stanton retired from the Survey in 1935, however, he continued to act as the Custodian of Mesozoic Invertebrates at the US National Museum (now the National Museum of Natural History) until his death in 1953. Throughout his career, Stanton managed a balancing act between acquiring remarkable collections from his fieldwork efforts and the responsibilities of the multiple positions he held at the USGS. Stanton’s success is both reflected in the history of the USGS and his contributions to the Menlo Park Collection. UCMP is honored to permanently house this collection and to manage its care and access for current and future scientists. The collection is a remarkable paleontological record that is being updated and cared for by UCMP students and scientists in the 21st Century.

Invertebrate specimens

Various Cretaceous invertebrate specimens collected by Stanton during September of 1900 in Colusa County, CA. USGS Locality Number 2290. Photos by Michelle Sparnicht.

Reports from Regatta: Two Cal Alumni and the USGS Menlo Park Collection

Nelson letter and envelope

The letter from Cliff Nelson to Warren Addicott.

As undergraduate work-study students recataloging the United States Geological Survery (USGS) Menlo Park Invertebrate collection at the UCMP, we've come across the names Nelson and Addicott time and time again in extensive database entries or on the original, yellowing locality cards paired with each specimen. The names of the paleontologists and geologists responsible for collecting these fossils in the Menlo Park collection are largely unknown to us, but found immersed within the aging drawers of the invertebrate fossils were several curious and antiquarian documents that have brought these names to life. One recently discovered letter, written by UC Berkeley alumnus Cliff Nelson records his activities in the collections during the summer of 1974.

In the letter, Nelson discusses his dissertation work that focused on migration patterns of Neptunea, a large sea snail indigenous to the North Pacific. While studying the migration traces of Neptunea through the North Pacific and to the North Atlantic and California Current, Nelson proposed to elevate Neptunea beyond the level of subgenus. His dissertation interpreted Neptunea as a genus, with the inclusion of 56 named species — half of which are extinct. The letter goes on to explain Nelson's use of the Menlo Park collection and the late nights he spent scavenging through the collections, searching for invertebrate specimens to support his dissertation.

The letter also delivers some insights on other individuals who played an important role in Nelson's research. Warren Addicott, the recipient of Nelson's letter (and another popular name found often in the Menlo Park Collection), obtained his doctorate at UC Berkeley in 1956 and led a distinguished scientific career at the US Geological Survey. The letter concludes with Nelson's gracious thanks to Addicott for his help with his dissertation and an acknowledgment to Dr. Stearns McNeil, another familiar name associated with the Menlo Park collection and the USGS.

After receiving his Ph.D. from UC Berkeley in 1974, the year the letter was written, Nelson went on to publish over fifty articles in refereed journals and books. His work primarily focused on the history of scholarship, ideas, and institutions in natural sciences. Currently, Nelson works as a geologist and historian at the USGS. In 2011 he received the Friedman Distinguished Service Award from the Geological Society of America's History and Philosophy of Geology Division.

Letters such as this one help us discover the identities of the names we come upon so frequently. This is just one of many documents that shines light on the Menlo Park collection and allows us to reconstruct the UC Museum of Paleontology's historic and scientific past.

Neptuneidae specimens

USGS gastropod specimens (Family Neptuneidae) studied by Nelson during the course of his doctoral study at UC Berkeley. Left: A specimen from USGS Cenozoic Locality M863 Pliocene, Gubick Formation of Alaska, Colville River. Right: A specimen identified by Nelson as Beringius beringii; from USGS Cenozoic Locality M860 Pleistocene, Gubik Formation near Point Barrow village, Alaska. Both specimens were collected by John O'Sullivan pre-1960.