We're Tyler Lyson and Ian Miller, paleontologists who recently discovered fossils that capture the million-year timeline of life after the dinosaurs died. Ask us anything!

A few years after the impact, what does life look like for the survivors (food, climate)? Did any consideraly large mammal survive? How come smaller dinosaurs did not dominate the earth and were replaced by mammals instead?

It's filled with charcoal and ferns. Not alot of organisms made it through the event so it was pretty quiet afterwards. The largest mammal was the size of a rat. Small dinos dominate afterwards? Good question. We think the smallest dinos were specialists and they were still pretty darn big - at least 5 to 10 kilos.

How quickly did the extinction event occur? Have you seen evidence of a rapid kill within in a day, or was it a long drawn out event over a few years or more?

How quickly did life and biodiversity rebound?

The extinction was geologically instantaneous but may have occurred over decades to centuries though many, many organisms died the day the asteroid hit. For the second question: watch the NOVA!!! Its all in there. Short answer, pretty fast in our estimation (100,000 years+).

The extintion on land was massive, do we have some idea of how much was affected the life on water??

The extinction was equally massive in the oceans. Different kill mechanism but still disastrous.

If you were visiting the city of Denver, lets say this weekend, where would visit to get your paleontology itch scratched?

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Obviously asking for a friend, a stranger really.

Denver Museum of Nature & Science!! Come check out: After the Asteroid: Earth's Comeback Story, where we have the best fossils from this discovery on display.

Thanks guys, big fan of your work. My wife and I were wondering if you’d put together a public exhibit there yet and I see now that it opened November 1st which was faster than I’d expected. So we’ll be down soon to check it out. I’m a plant guy, member of Colorado Native Plant Society, DBG, etc so I’m pretty interested in the legume you found dating 700K after the event. I skimmed your recent Science paper and it seems as far as what’s been found worldwide so far the evolution of FABACEAE can’t be pinned down currently to tighter than the Western Hemisphere. Is that right and do you think it can be made more specific geographically in the future, like with ASTERACEAE and CACTACEAE?

This is a great question and one I am currently working on! We don't know the answer yet. We'll be using some of the latest molecular phylogenies and some of the new fossils that have been found in South America, as well as our own, to try to answer this very question. We can't determine whether or not our fossil legume belongs in the crown or stem of Fabaceae.

What has been the scariest find so far?

Any surprising discoveries? Like things you didnt mean to find.

The biggest surprise was the legume! We did not expect to find the world's oldest legume. Prior to this discovery the oldest legume was from southern Argentina.

Are chickens dinosaurs?

Yes. They are avian dinosaurs. Ponder that at dinner tonight. https://artsandculture.google.com/exhibit/the-dinosaur-on-your-dinner-table-denver-museum-of-nature-and-science/xwLigahP7vAcLA?hl=en

Is it true that turtles are basically the same since the dinosaurs age?? Or is it a myth?

Do you find turtles on this time period?

Tyler says: yes! They do change but their overall body plan has remained the same since 210 million years ago!

What kinds of plant life did we see right after the K-Pg extinction? I’ve always heard about the animal life but never plants

The best way to think about it is that the KPg was a massive disturbance to the worlds ecosystems. Plants that like disturbance (and there are some) do very well after the boundary! Ferns, a few weedy flowering plants, and a few warm loving conifers.

What do we think factored into the survival of the smaller animals (or the inverse) ?

Why did bird-like dinosaurs have higher survival rates?

Smaller animals tend to need fewer resources. Other factors contributing to survival across the KPg boundary include having a slow metabolism, living underground or under fresh water, not being a dietary specialist, etc. What survived this extinction event are enduring questions.

What's the public's biggest misconception about the extinction of the non-avian dinosaurs?

That there still exists a debate between the ultimate cause being either the asteroid or massive volcanic eruptions. The data overwhelmingly support a catastrophic and instantaneous extinction caused by an asteroid.

Is it true that most of the species that survived were those that were underground, as they suffered the least from the cataclysm?

Underground or under freshwater. These were the best strategies to survive, plus being able to eat detritus.

Is there a significant difference in the number of species dedicated to "waste removal" ie flies, dung beetles, vultures, etc now than there were during this time frame?

Interesting question, but the fossil record isn't quite there to address this question.

would you rather fight one fossilized horse sized duck or one hundred fossilized duck sized horses?

These are the questions that Tyler and I fight about on a day to day basis. We're split. I prefer tiny ducks.

What was it like finding the fossils, did you know how much of an impact this might have on the world?

PURE JOY! And we really did think we had a big discovery right from the beginning.

Was the asteroid impacted in the current location of the gulf of Mexico?

Yes, basically. Its partially on the Yucatan Peninsula. Cancun is just to the east.

What's your favorite find, and what's your favorite fossil someone else found?

For this work, the big Eoconodon skull (Tyler's answer); for me, it's gotta be the worlds oldest legume pods found by Aeon, one of our high school students. Stay tuned for more amazing finds?

!! i mean

Which dinosaur types, if any, made it through 10/100/1000 years after impact?

I'd be really interested in learning how dinosaurs adapted as the planet started repairing itself

Tyler has found the dinosaur closest to the boundary. It's 4 cm below the impact horizon. It is a horned dinosaur. So far, we haven't found any non-avian dinosaurs above the boundary anywhere on Earth.

What was the species to precursor primates living at this time?

Purgatorius. Mouse-sized creatures. They are the ancestors to us and bats and everything in between.

What would life most likely be like today if the asteroid didn’t hit the earth?

Dinosaurs would still dominate and we humans would not be here!!

Can nature, over a very long period of time, re-evolve some species again, from the ones that went extinct because of the impact?

This is one of the sobering aspects of extinction. It is forever. Though we often talk about recovery from mass extinction what is really happening is a new world is emerging with new species. We never go back to the pre-extinction worlds and the life in them.

Fascinating. From what you two know, how rich was biodiversity?

More vegatation than dinosaurs or vice versa? How much influx did the K-T boundary receive?

Always more plants than vertebrates except in the coldest ecosystems (think the Arctic/Antarctic). Could you rephrase your second question?

Have you worked with anyone studying the Tanis fossil site in ND? They are studying evidence of the actual day the dinosaurs experienced the killer asteroid.

The area where Tanis was discovered is our other main field area (Tyler grew up there!), and we are really looking forward to seeing future work coming out of this amazing site.

How many years did it take for truly dominant apex predators to rise up the food chain, and what were they? Id imagine that some went uncontested and unrivaled for a period. What are some creatures that directly survived the extinction event and are still alive today/have recently gone extinct (by human intervention or other means)?

Your first question is an open question. The apex predators changed pretty quickly from post K/Pg extinction right up until today. Turtles did the best during this mass extinction event. In fact the biggest animal to survive was a large softshelled turtle whose lineage essentially went extinct last spring as the last female of this lineage died. Today, over 50% of turtles are critically endangered/endangered/vulnerable.

What was the most memorable piece of human made garbage you encountered during these expeditions? Is there anything that you were shocked to find in a remote area?

Mortar shells! The field area was once used by the US military and is littered with 50 caliber bullets and other projectiles! The bullets and mortar shells are from WWII era (we think).

Is there evidence in your research that speaks to why there is over representation of marsupials in Australia and the surrounding regions?

We're still waiting on a similar K-Pg boundary section in Australia. Only one marsupial survived the extinction in North America. I think its still a pretty big and open question about all those marsupials in Australia.

Is there any effort to expand this picture to include major geological changes (ice cap melting and resulting erosive forces) volcanic activities and marine life during the same period?

Yes, we are currently linking our study with intense volcanic activity happening at the same time in India--post-KPg.

How many fossils have you accidentally “destroyed” in your career?

I want to get into fossil hunting by my number one fear is that because of my lack of experience excavating I’ll destroy numerous specimens before I learn not to.

How do you handle this conundrum?

None!! We both may have damaged some early in our careers, but that is the only way to learn!

How many mammalian and avian species are represented in the fossil record from that million year period after the K-T boundary? How is the coverage across the world? (In comparison with other time periods.) How does the mammal skull discovery fit into that record and expand our understanding of that time period?

What is our best understanding of the time it took for all dinosaur species to disappear? Was it purely environmental factors that drove the extinction or did some species survive to be out-competed post K-T? (And how well would we even be able to determine this from the fossil record?)

Thanks for the AMA! Always excited to see scientists do these--great outreach opportunity. I ended up going into physics, but paleontology was the first field that got me excited about science and the scientific process.

We've found 16 species of mammals from this interval of time, but other rock units from the same interval have nearly twice that many. No bird fossils have ever been found in the first million years after the extinction of the dinosaurs. The mammal skull discovery provides much more complete material to determine 1) size of their brains 2) inner ears to determine sense of balance and where they are living 3) bite force 4) and generally what these animals looked like! We hope to use these fossils to get a better understanding of who, amongst modern mammals, they are related to and what their overall ecology was 65 million years ago. Dinosaurs disappeared geologically instantaneously (10-1000s of years). It likely was a combo of environmental (i.e., giant asteroid and subsequent fallout) and post K/Pg competition (i.e., detritus feeders did better than specialists such as herbivores or carnivores). But, to your point, the fossil record has its limitations.

Based on your findings, did Epstein kill himself?

I've got our best people on it.

Do we know what kinds of birds survived the K-T extinction, and why birds but not other dinos?

Yes, we have a good idea. Ground-dwelling birds seem to be the ancestors to all living birds. The idea is that if the forests are destroyed, anything that lived in those forests died too.

What surprised you about your findings?

How long was the Earth's climate affected by the KT extinction event?

What flora/plants did well following it and what died?

I think the biggest surprise was just how well all of the datasets aligned. The climate seems to impact the recovery of the forests, which in turn impacts the recovery of the mammals. The climate was affected for ~50-100K years. Ferns and palms flourished in the early aftermath. Most plants and animal species (75% or so) go extinct.

What was the most exciting discovery/theory that has changed the way paleontology views that period of Earth history, if there was one?

Do you think paleontology is a field of study that has already been mostly cracked open by the modern science or are there many things to be yet discovered?

The asteroid impact theory put forth by Alverez et al. in 1980 completely changed the way paleontologists viewed this specific interval of time. There are so many new things to be discovered in paleontology! New fossils and new techniques continue to push the field forward. There are more species of dinosaurs being named now than in any other point in our history.

Is it true that a stratum was found showing fallout from the K/T asteroid strike as it was occurring?

Yes! We have places around the world preserved that show the iridium anomaly and spherules, which are both types of fallout from the K/Pg asteroid.

Are Dr. Lyson’s discoveries going to be displayed in Denver’s Museum of Nature and Science? I’m sure there is much information to be gathered from the fossils, information that many of us would love to witness as well!

Our discovery is currently on display at the Denver Museum of Nature & Science!! You can also check out: coloradosprings.dmns.org

We always hear about the meteor impact that killed the dinosaurs but when I am curious about was how long did that take and is it possible to know? Was it a matter of years or centuries and when about do we estimate the last dinosaur to have truly died?

The geologic record doesn't really allow us to discern between 100's and 1000's of years so its still an open question. We know what happened in terms of an asteroid hitting earth but we need to hypothesize the series of events that happened in the ensuing days to years. We do know that there are no dinos above the boundary!

Have you found any fossils that could have been distantly related to humans during this period?

We don't have any early primates but we do have early placental mammals. They gave rise to almost all mammals that live on earth today! Think whales, zebras, bats, humans, horses, and your cat!

What was most interesting about your finds?

This is complex but some highlights are how quickly life rebounded after the extinction (100,000 years is quick to paleontologists) and the interconnection between climate, plants and vertebrates.

Is global warming real?

Yes. Absolutely.