This July my two major research tracks both have matured enough to be recognized by my peers via @science.org. Gratitude to my lab people & collaborators. I hope you enjoy reading the papers as much as we enjoyed working on them:(5/5) www.science.org/doi/10.1126/... www.science.org/doi/10.1126/...

Before I gave up completely on a research career, I got a job (lucky!). Four years later I got my current gig, where I felt free to "Be All You Can Be". The freedom to pursue interesting questions was FULL of false starts & dead ends, but a few projects flourished. My team endured & got funded (4/5)

Later, on the job market I often felt out of place during interviews: many open positions targeted specialists. I was doing multiple lines of research that have not yet led to major results or publications. I almost chose just one aspect to drill down on. But for better or worse, I never did. (3/5)

As an undergraduate just getting started in research, I could not decide which topic I loved more: functional morphology and biomechanics, or vertebrate paleontology. My mentors in two labs (S. Patek, S. Hopkins) let me work on two senior projects so I didn’t have to pick one. (📷Getty Images)(2/5)

#FossilFriday flashback: My lab published two major papers this month on 1) dental functional morphology and 2) vertebrate paleontology & paleobiogeography. It made me so proud of the research teams I've been a part of over the past decade, but it also prompted reflection on my academic path (🧵1/5)

In sum: our new data & analyses provide a refined view of pre-GABI mammal movements, and underscore the untold stories in the latitudinal dimension of the GABI. Collection of primary field data is unreplaceable. Central America and the Panamanian land bridge region need more fieldwork! 🔨🪨🦴(11/11)

What’s more: we also noticed a tendency for larger-bodied and dryer-environment adapted mammal clades to participate in the holding pen. This matches our stable isotope data from Mexico, suggesting that vegetational shifts played a role in which mammals made the journey in and across Mexico (9/11)

We then detected a different phase between the holding pen and GABI pulses, when faunal connectivity increased between Mexico and the rest of the Americas. This connectivity increased asymmetrically, with more North American taxa in Mexico earlier than increases in South American taxa there. (8/11)

We also observed an accumulation of higher latitude mammals in Mexico from 10-7 Ma. The pattern represents a ‘holding pen’ previously proposed by Flynn, Woodburne, and colleagues. However, this holding pen is more than twice as old as what they saw with earlier, less complete fossil records. (7/11)

We estimated diversification rates and faunal connectivity patterns across the Americas, vetting taxonomic occurrences and accounting for uncertainties in fossil age ranges. We discovered a latitudinal signal of fossil mammal movements in the 7 million years leading up to GABI pulses (6/11)

We collectively conducted more than 30 years of fieldwork in Mexico in 12-3 Ma deposits. We analyzed this and other published data by treating Mexico as an intermediate biogeographic unit between higher latitude North America and South America, testing for latitudinal gradients in dispersal (5/11)

Some analyses of molecular data have also suggested that a Panamanian land corridor may be as old as 15 million years or older. Such an ‘old isthmus’ hypothesis has not been rigorously tested using the mammalian fossil record, and especially not with low-latitude data. (📷: O'Dea et al. 2016)(4/11)

Although the main GABI pulses started around the same time as the appearance of a persistent Panamanian land bridge, there has been conflicting findings as to the tempo and mode of pre-GABI land corridors. Some studies propose a Middle Miocene closure of the Central American Seaway (3/11)

GABI is a series of organismal dispersal events between the Americas that helped establish their current day biodiversity patterns. It has been most intensively studied in mammals, with the fossil record showing major pulses of dispersals starting around 3 Ma (image: Woodburne 2010, X. Wang) (2/11)

Exhilarated to share a 2nd @science.org cover article this month from our lab @ucberkeleyofficial.bsky.social! A collaboration with US & Mexico colleagues on the role of a Mexican biogeographic holding pen in shaping the Great American Biotic Interchange (GABI)(1/11) www.science.org/doi/10.1126/...

Our newest paper on mammalian dental evolution, out today as the cover article in @science.org, lead by @narimanechatar.bsky.social with a team of fantastic early career scientists!!! 🎉🥳 “Performance trade-offs define a fundamental dental dichotomy in mammals” www.science.org/doi/10.1126/...

Excited for a major paper drop tomorrow with @narimanechatar.bsky.social! Watch this space if you like mammals and teeth!

Granitic intrusions forming sheer cliffs in the Hua Shan (华山) UNESCO World Heritage Site. Our cable car gliding over 2000-m high peaks that formed over the past 70 million years.

The Badaling Great Wall in the Yan mountains (燕山) and dinosaur-age granites and limestones originating from the Jurassic/Cretaceous Yanshanian tectonic events.

The final perspective of Smilodon populator a prey sees. Museo Argentino de Ciencias Naturales. #FossilFriday

Humanity is experiencing technical difficulties at the moment with humanity-ing, please check back later…😓 (seen in San Francisco).

The gigantic ground sloth Megatherium at MACN in Buenos Aires, Argentina. The size of this herbivore is difficult to appreciate from the photo. A human would only stand near hip height (on the platform) next to this Ice Age megamammal! #FossilFriday

So excited to see dueling Smilodon populator in front of the Museo Argentino de Ciencias Naturales! Spending this week in Buenos Aires looking at South American fossil mammals.

Mesquite Flat Sand Dunes in Timbisha (“Death Valley National Park”), home of the Timbisha Shoshone.

Our BioSci library did this Valentine’s themed mystery book feature at the front desk, where you can unwrap a secret valentine book to check out if the keywords catch your eye. I couldn’t resist this one, which seems to be edited by none other than @arctomet.bsky.social!

It’s a wrap for my vertebrate morphology class. Students surveyed the vertebrate fossil record, functional anatomy, phylogenetic comparative methods, geometric morphometrics, scientific writing, + more! A doubly meaningful experience for me because I took this class as an undergrad 24 years ago! 💙💛🐻

Safe travels all #2025SVP folks! En route to Birmingham via London…and who am I to argue with the NHM’s kids pack swag? 😁

Celebrating #NationalFossilDay with a new paper describing specimens of the most whimsical of weasel relatives, leptarctine ("slender bear") mustelids, from the collections of @ucmpberkeley.bsky.social. Their teeth are so much fun to look at! 🦷 doi.org/10.5070/P9.4... (Cover image by P. Holroyd)

Studying wrist and ankle bones for fossil id and found it amusing how carpals have wired names like magnum and unciform but tarsals have tired names like cuneiform 1, 2, 3. Like they ran out of cool names for bones by the time they got to feet 😆