Ancient lizard pregnant for 120 million years

The fossilised lizard Yabeinosaurus tenuis was pregnant with at least fifteen babies at the time it died (Original photo: Jie Zhang/Susan Evans)

Scientists have discovered the oldest-known fossil of a live-bearing lizard. The fossilised remains of the ancient pregnant lizard, dated between 120 and 125 million years old, show the skeletons of more than fifteen developing embryos in utero.

The earliest live-bearing (viviparous) lizards were thought to have originated during glacial episodes in the Pleistocene, no earlier than two million years ago. However, the recent discovery of the fossil suggests live birth evolved at a similar time in both lizards and mammals.

Susan Evans, a professor from the University College London and co-author of the journal article published in Naturwissenschaft, discovered the fossil in Lower Cretaceous geological deposits in the Jehol region of Northeast China.

“We previously thought that lizards adapted to live birth after mammals, but now it looks like it happened at roughly the same kind of time,” Evans told PhysOrg.com.

The fossilised lizard, identified as Yabeinosaurus tenuis, was most certainly viviparous; Evans found no trace of an eggshell surrounding the embryos and their skeletons indicate they were almost fully developed and probably within days of being born.

Susan Evans, co-author of the research, determined the developmental stage of the embryos by studying their tiny skeletons (Original photo: Jie Zhang/Susan Evans)

There are very few examples of fossilised pregnant reptiles, since it is incredibly rare that the skeletal remains of embryos are well-preserved in the fossil. Previous fossils have revealed that some ancient aquatic reptiles were also viviparous, but this is the most ancient primarily land-dwelling viviparous lizard to be discovered.

In the past, some “pregnant” fossils were in fact cases of cannibalism, where the remains of a juvenile reptile in the gut of an adult were mistaken for an embryo. However, there is no mistaking these embryos for this fossilised lizard’s lunch - the positions of the fifteen little skeletons correspond to the location of the paired uteri found in modern-day lizards.

My birthday card!

I turned 25 yesterday, so here's a lizard bustin' a move - thanks Hope!

I'm a Scientist, Get Me Out of Here!

Why do mirages form? Why can birds sit on powerlines and not be electrocuted? What is string theory?

These are just some of the burning questions Australian high school students had during June on “I’m a Scientist, Get Me Out of Here!”

“I’m a Scientist, Get Me Out of Here!” is an online science event targeting high school students in Years 7 to 9. Successfully orchestrated in the UK since 2008, a pilot of the program was run recently in Australia from June 14 to 24. I was one of fifteen scientists selected to take part in the event.

Up for a challenge? Try explaining string theory to a class of teenagers in an online chat session!

The program is an opportunity for high school students to chat online to real-life scientists about science research and careers in science. The hope is that students learn more about what it means to do science, while the scientists learn to explain and communicate complex science simply, concisely and in an entertaining way.

We created online profiles so that the students could get to know us a little – we explained the sorts of things we do each day as scientists, our research interests, and what we like to do in our spare time.

Students then posted questions on the site for the scientists to answer. These often required creative answers to pique students’ interest, since other competing scientists (Full credit to them!) had usually provided an answer before I’d read the question. Some of these questions were really insightful, while others were hilarious. My favourites would have to include “If I stand next to gamma radiation, will I turn into the Hulk?”, and “Do miniature dachshunds get nipple rash when pregnant?”

Teachers also booked their classes in for live MSN-style chat sessions, during which students fired questions at us scientists and waited for our answers during the chat. It was frantic but strangely exhilarating typing like a maniac to give two or three line answers to questions like “How did the big bang happen?”, “Why do we dream?”, “What subjects should I pick for year 11 to get into veterinary science?” and “Do you like Justin Bieber?”

Charles Darwin and Albert Einstein had to compete with Justin Bieber for students' attention during some chat sessions

After a week of online questions and chats, the students must decide which scientist they like the best and which one gave the best answers. The fifteen scientists were split up into three zones, each containing five scientists, and the scientist judged the best in each zone won $1000 to put towards a science communication project of their choice.

But the judging process was brutal! Like the reality TV shows, “I’m a Celebrity, Get Me Out of Here!” and “Big Brother”, scientists were dumped from the competition one by one during daily evictions. Our future in the competition hung in the balance as fickle teenagers decided our fate. What makes a scientist “better” than another in the eyes of a thirteen year old?

I asked myself – did I answer enough questions? I had answered over one hundred questions online, but there was another fifty I hadn’t had time to get to. Was my profile picture cool enough or was it just corny? Were my answers to the questions interesting enough? In the end, I was the second of the five scientists in my zone to be evicted. A big “EVICTED” banner was posted across my profile picture and I watched the remaining three scientists fight it out, answering question after question, offering really insightful answers for the students.

The final eviction was down to the wire – Aimee, a bubbly honours student from Monash University, was voted the favourite scientist, narrowly beating Mat, a chemistry lecturer from Sydney University. Aimee plans to use the $1000 in prize money to set up a science writing prize for high school students.

Phew! I was relieved that my two frantic weeks of being an online science guru was over, but I’d do it again in a flash and I encourage other scientists to get involved next time round. I found getting immediate feedback from the students during the online chat sessions really rewarding, even addictive – while I might wait weeks or months for results and feedback from my lab work, I could see what the students thought of my answers within a few seconds. I really think online events such as this are an important complement to face-to-face methods of science communication for kids, and I will definitely be tuning in to the next “I’m a Scientist” event.