Associated Smithsonian Expert: Kathy Hollis, M.S.

Kathy Hollis with Triceratops obtusus, collected in 1890 by John Bell Hatcher

Courtesy of Adrienne Block

Kathy Hollis is the collections manager in the Smithsonian National Museum of Natural History Department of Paleobiology. As a kid she would give rocks as gifts, assuming everyone thought rocks were as cool as she did. She majored in geology at the College of Wooster in Ohio and went on to finish a master’s in geology at the Ohio State University in 2005. It was at Ohio State that Kathy realized her love for museum collections. She finished a master’s in Museum Studies at the University of Colorado at Boulder in 2008 specializing in collections care and museum-based research. Kathy has been at the Smithsonian since 2010 and helps to care for one of the largest fossil collections in the world. Her work involves getting the information about what organisms lived when and where out of the collection drawers and making it digital, accessible, and searchable online. Kathy brakes for fossil echinoderms.

Meet our associated expert

This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.

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Inside of a fossil ostracod shell (Echinocythereis garretti) from the Miocene
Photo by Smithsonian Institution, Department of Paleobiology

About Ostracods (Class Ostracoda) : Paleobiology

Ostracods are small organisms with hinged, two-part shells that are common in the fossil record. Ostracod remains can form huge deposits and are the main component of some shelly limestones (coquinas) that are used for building. They first appeared in the Cambrian more than 500 million years ago and are still abundant today. The evidence an ostracod leaves behind is its shell. Because they are widespread and well-preserved, ostracod shells serve as ecological indicators of past conditions. The location of fossil ostracods and chemistry of their shells provides paleobiologists information about water depth, temperature, salinity, and nutrients. Several indices of paleoclimates have been developed based on ostracod distributions. For example, the MOTR (Marine Ostracod Temperature Range) extrapolates from temperatures tolerances of modern ostracods to infer paleoclimates where fossil ostracods are found. The oil industry even uses fossil ostracods to find sites for exploration because ostracods are associated with particular types of rock.

Fossil crab claw
Photo by John Steiner, Smithsonian, National Museum of Natural History

About Arthropods (Phylum Arthropoda): Paleobiology

Arthropods have been on Earth for more than 540 million years, and were diverse almost from the beginning. Different lineages of arthropods, such as crustaceans, diverged as early as 525 million years ago. The evolution of an external body covering (the exoskeleton), and the presence of body segments and paired appendages (mouthparts, legs, claws, antennae) signaled the transition from early worm-like precursors to arthropods. While modern arthropods live in nearly every habitat, the earliest arthropods were probably tiny, bottom-dwellers scavenging detritus at the bottom of warm seas. The enormous success of arthropods is at least partly due to their appendages. Located on all body regions, their appendages became specialized especially for feeding through the mouthparts, but also for getting oxygen through respiration (gills), reproducing (elaborate external genitalia), and moving around including walking, swimming, and/or flying. The gradual adoption of a modular body plan with multifunctional appendages has allowed arthropods to thrive in an impressive variety of environments.