Joshua Andrew Ludtke

Master's Candidate in Evolutionary Biology

San Diego State University
Department of Biology
5500 Campanile Drive
San Diego, CA  92182-4614

Phone: 619.594.7432
Email: joshualudtkeATgmail.com

About me...

Short version: My C.V.

Long version:

Hello, I'm currently an eighth-semester master's level graduate student, who is on track to finishing up my research during this summer and then quickly shove all my reprints into boxes and move to a different program/school/state/country.

My undergraduate education was conducted at Occidental College, wherein I majored in Geology under D.R. Prothero. During that time I was involved in several magnetostratigraphic projects, both in the field collecting small calibrated sections of stratigraphic columns, and in the laboratory (at the California Institute for Technology's paleomag lab) analyzing these small chunks of sedimentary rock for the faint traces of paleomagnetic direction they showed. My senior thesis looked at the systematics of the basal protoceratid Leptoreodon, a middle Eocene genus of fossil cetartiodactyl widely-spread through North America. My advisor and I examined and measured fossil collections of this genus, particularly at the Los Angeles County (LACM) and San Diego Natural History (SDSNH) Museums, with supplementary information from the University of California - Berkeley (UCMP), University of California - Riverside (UCR, currently held at UCMP) and American Museum of Natural History (AMNH) collections. My regrets concerning that project are:

1) I never visited the AMNH during this project.
2) We never viewed the Texas specimens housed at the University of Texas - Austin's Texas Memorial Museum (TMM) and so do not know for sure what species existed there.
3) Ditto for specimens reported from Saskatchewan.
4) We never examined the genus Leptotragulus and so I still have my doubts about whether it and Leptoreodon are distinct genera. (thankfully I saw a poster about this at SVP 2006 and was placated)
5) Any typos that survived the editing process.

I graduated from Occidental College in Spring 2004 and the next semester began attending San Diego State University. Here I am a student in the Evolutionary Biology program in the J.D. Archibald lab. After coming to the conclusion that an early duo of ideas would either be unfeasible or redundant, I began my current project: conducting a systematic revision of the basal oreodont group Agriochoeridae. As far as we can tell, oreodonts were the most abundant terrestrial cetartiodactyls in North America for most of the Cenozoic, from their appearance in the middle Eocene until the middle Miocene when other, immigrant taxa hypothetically outcompeted the less-derived (and possibly non-ruminating) oreodonts. Agriochoerids, particularly species now in the genus Protoreodon, were the figurative flag-bearers for this highly successful group, dominating fossil localities during the middle Eocene before (hypothetically) evolving into several lineages of merycoidodontid oreodonts and the genus Agriochoerus. Aside from being a relatively homoplastic organism for most of the Oligocene, Agriochoerus is also interesting because it is one of a few hoofed mammals (and the only cetartiodactyl) to possess claws. My project is currently looking at dental, cranial and post-cranial (mainly limb) material of these fascinating mammals. Questions I'm pondering:

1) Can the evolution of claws be correlated with the evolution of dental characters in this group; in other words, was an observable change in diet or feeding techniques correlated with this novel morphological change?
2) Can a clear line be drawn between species of Protoreodon which led to derived members of Agriochoeridae and those which led to Merycoidodontidae?
3) Despite the relative abundance of homoplastic characters in this group and relative rarity of complete specimens during the Eocene-Oligocene transition, can a reasonably valid and robust phylogeny for this group be developed?
4) Not that I'll ever know for sure, but why claws?
5) And it's outside the range of my project, but where do oreodonts fit in the complex cetartiodactylan family tree?

This project has so far been the most exciting, interesting, and demanding endeavour I've ever put myself to. I've looked at over a thousand jaws from creatures over a twenty million year period of time. I've added a few more museums to my lifelist, the list nowadays is: AMNH, SDSNH, LACM, UCMP, University of Oregon (UO), John Day Fossil Beds National Monument (JODA), Carnegie Museum (CM), United States National Museum of Natural History, Smithsonian Institute (USNM), Academy of Natural Sciences in Philadelphia (ANSP), Yale Peabody Museum (YPM), Texas Memorial Museum (TMM), Denver Museum of Nature & Science (DMNH), University of Colorado Museum (UCM) and New Mexico Museum of Natural History and Science (NMMNH&S). And the really disturbing thing about it all is that the more I look at fossils, the more I want to look at fossils.

One of these days I will finish this project and start that doctoral program I should have already started . As far as future research goes... I'm interested in systematics of the Merycoidodontoidea but I have my doubts about how useful dental characters are in understanding them in a cladistic manner. So I'd be enthused to do a study on the relationships between agriochoerids and other oreodonts with morphological characters besides just teeth. How weird. Some bigger-scale questions I wonder nowadays:

1) How closely related were protoceratids and oreodonts? Their evolutionary histories are somewhat similar (appear and become widespread in only North America in the middle Eocene, reduce in numbers during E-O transition, main survivors of that transition are hypsodont, survive until late Miocene or Pliocene) and it begs the question of whether this is in any manner due to a phylogenetic signal.
2) Related to this, are protoceratids and oreodonts North American representatives of a middle Eocene, worldwide range expansion of primitive ruminant cetartiodactyls, which were subsequently driven to extinction by competition against the more derived, Eurasian immigrants Cervoidea and Bovoidea?
3) What are the biogeographical origins of Cetartiodactyla and Ruminantia? Or can we even tell?
4) Where does Cameloidea fit into Cetartiodactyla? This question does not get as much attention as the Whippomorpha issue, but morphological and molecular evidence disagree on this issue strongly.
5) Related to the above question, if camels evolved selenodont dentition and a form of rumination independently of Pecora, did these traits evolve in a basal pecoran or multiple times within that clade?
6) Can I afford to do the research I would like to for my PhD?

Publications list (also in my C.V.)

Calvano, G, DR Prothero, JA Ludtke, and EB Lander.  2008.  Magnetic stratigraphy of the Eocene to Miocene Sespe and Vaqueros Formations, Los Angeles and Orange Counties, California.  Natural History Museum of Los Angeles County Science Series 41: 43-61. (PDF here)  

JA Ludtke.  2007.  Agriochoeridae; pp 151-156 in: DR Prothero and S Foss (eds.), The Evolution of Artiodactyls. John Hopkins Press, Baltimore, MD.  (PDF here)

Prothero, DR and JA Ludtke.  2007.  Protoceratidae; pp 169-176 in: DR Prothero and S Foss (eds.), The Evolution of Artiodactyls. John Hopkins Press, Baltimore, MD.  (PDF here)

Ludtke, JA and DR Prothero.  2004.  Taxonomic revision of the middle Eocene (Uintan-Duchesnean) protoceratid Leptoreodon (Mammalia: Artiodactyla).  New Mexico Museum of Natural History and Science Bulletin 26: 101-110. (PDF here)  

Prothero, DR, JA Ludtke, and SG Lucas.  2004.  Magnetic Stratigraphy of the middle Eocene (Duchesnean) Baca Formation, west-central New Mexico.  New Mexico Museum of Natural History and Science Bulletin 26: 55-58. (PDF here)

Page last slightly updated: 05-30-2008