econintersect.com
       
  

FREE NEWSLETTER: Econintersect sends a nightly newsletter highlighting news events of the day, and providing a summary of new articles posted on the website. Econintersect will not sell or pass your email address to others per our privacy policy. You can cancel this subscription at any time by selecting the unsubscribing link in the footer of each email.



posted on 11 June 2016

Fossil Teeth Reveal The Secret Rise Of Mammals Millions Of Years Before Dinosaurs Became Extinct

from The Conversation

-- this post authored by Elis Newham, University of Southampton

What would have happened if an asteroid hadn't killed the dinosaurs? Perhaps mammals wouldn't have evolved to become the planet's dominant group of animals and humans would never have existed.

We're certainly used to the idea that it was only after the dinosaurs (apart from birds) became extinct around 66m years ago, that mammals were able to develop and spread around the globe. But new research suggests this picture of Earth's evolution may not be completely accurate.

Work by a team that includes me and other palaeontologists from the universities of Chicago and Southampton has unveiled a new level of detail of early mammals. We discovered that the therian mammals (the kind that gave rise to most modern mammals) were actually beginning to diversify between 10m years and 20m years before the Cretaceous mass extinction event that wiped out the dinosaurs.

This finding reflects the considerable changes in our understanding of the early evolution of mammals, thanks to exceptional fossils found over the last few years.

Previously, most palaeontologists thought that mammal diversity was suppressed by the dominance of dinosaurs. This was largely based on the fact that many of the early mammal fossils that had been found were from small, insect-eating animals with very similar feeding habits and life histories. But with the help of some astounding new fossils, including several from China, we have shown that mammals at this time were much more diverse than this suggests.

We focused on studying several aspects of early mammal diversity, including the number of species through time and how these animals differed in both their physical structure and the way they lived. We also looked at how these things changed through time, particularly during the period either side of the extinction event. To do this, we studied the shape of teeth of hundreds of early mammal specimens in museum fossil collections.

Greater diversity

Mammal teeth are highly developed, with uniquely complicated series of cusps, troughs and pits that perform precise functions for feeding. This means the specific shape of teeth can offer a wealth of information on the lives of long-extinct animals.

Tracking changes in tooth shape through time showed us that the mammals that lived during the years leading up to the dinosaurs' demise had widely varied diets. This also helped us uncover another surprising finding. Mammals with the most extreme tooth shapes disappeared immediately following the extinction, which suggests that those that had the most specialised diets suffered along with the dinosaurs.

Answers in the teeth Dave Grossnickle

Our research follows other recent findings that dinosaur diversity was already decreasing before the extinction event, exactly as mammals were on the rise. So what caused this growing change in the prehistoric animal kingdom? One explanation is that the rapid spread of flowering plants (angiosperms) during the late Cretaceous period had a significant effect on the ecology of animal groups.

It is possible that mammals may have been able to adapt to this change in plant life and flourish while the dinosaurs could not. Small-bodied mammals may have been early adaptors to the range of new food sources (fruit and seeds), ecosystems and insect prey provided by the flowering plants. Meanwhile, non-avian dinosaurs felt more of the negative effects as these flowering plants took over their habitats, causing their traditional food sources to disappear.

Mammals' shaky start

Another traditional theory that our research questions is that mammals diversified rapidly immediately after the dinosaurs went extinct. Traditionally, the extinction has been seen as an ideal opportunity for mammal evolution to take off, but our findings suggest that early mammals were also hit by a selective extinction event. Some that could live off of a wide variety of foods were able to survive, but many other mammals with specialised diets went extinct.

By offering a more realistic image of the dynamics of mass extinction on mammals, our research may also provide important evidence of how mammals could be affected by man-made climate change. It raises the question of whether we should prepare for a similar selective extinction event in modern mammals as occurred 66m years ago.

This highlights how studying the fossils of long-dead organisms can actually help us to model our own effects on global ecosystems and habitats. In a rapidly changing world, the fossil record is a unique and unadulterated constant that may provide solutions far beyond what most people expect.

The ConversationElis Newham, PhD candidate, University of Southampton

This article was originally published on The Conversation. Read the original article.

>>>>> Scroll down to view and make comments <<<<<<

Click here for Historical News Post Listing










Make a Comment

Econintersect wants your comments, data and opinion on the articles posted.  As the internet is a "war zone" of trolls, hackers and spammers - Econintersect must balance its defences against ease of commenting.  We have joined with Livefyre to manage our comment streams.

To comment, using Livefyre just click the "Sign In" button at the top-left corner of the comment box below. You can create a commenting account using your favorite social network such as Twitter, Facebook, Google+, LinkedIn or Open ID - or open a Livefyre account using your email address.



You can also comment using Facebook directly using he comment block below.





Econintersect Contributors


search_box

Print this page or create a PDF file of this page
Print Friendly and PDF


The growing use of ad blocking software is creating a shortfall in covering our fixed expenses. Please consider a donation to Econintersect to allow continuing output of quality and balanced financial and economic news and analysis.


Take a look at what is going on inside of Econintersect.com
Main Home
Analysis Blog
The Expected Effects of Petitions to Improve the Monetary System
Energy and Falling Productivity
News Blog
Why Mosquitoes Bite Some People
September 2016 Texas Manufacturing Survey Improves Further Into Expansion.
August 2016 New Home Sales Decline On Lower Median Sales Prices.
U.S. Real Wage Growth: Fast Out Of The Starting Blocks - Part 1 Of 2
Who Works More Hours Per Week: Rich Or Poor Countries?
Infographic Of The Day: How The World's Most Iconic Logos Evolve Over Time
Early Headlines: Asia Stocks Down, Fed Wants Banks' Commodity Limits, Treasuries Being Sold, EZ Business Output Softens, France Contraction, Saudi's Boost Banks, Canada Tightens Borders For Chinese And More
Most Read Articles Last Week Ending 24 September
How Britain Owes Its Immigrants A Debt Of Gratitude
Super Mario, The Timeless Bestseller
Explainer: The Nine Swing States That Will Decide The Next US President
How Long Does Apple Support Older IPhone Models
What We Read Today 25 September 2016
Investing Blog
Monday Morning Call 26 September
We're Back Here We Started
Opinion Blog
Heading For A Fall? With Summer Over, Europe Must Face Up To Its Mounting Crises
What If We're In A Depression But Don't Know It?
Precious Metals Blog
War On Cash Turns To $20, $50, And $100 Bills
Live Markets
26Sep2016 Pre-Market Commentary: Wall Street Fractionally Lower, Volatility Expected In The Crude Markets Later This Week, First Presidential Debate Tonight
Amazon Books & More






.... and keep up with economic news using our dynamic economic newspapers with the largest international coverage on the internet
Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government



Crowdfunding ....






























 navigate econintersect.com

Blogs

Analysis Blog
News Blog
Investing Blog
Opinion Blog
Precious Metals Blog
Markets Blog
Video of the Day
Weather

Newspapers

Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government
     

RSS Feeds / Social Media

Combined Econintersect Feed
Google+
Facebook
Twitter
Digg

Free Newsletter

Marketplace - Books & More

Economic Forecast

Content Contribution

Contact

About

  Top Economics Site

Investing.com Contributor TalkMarkets Contributor Finance Blogs Free PageRank Checker Active Search Results Google+

This Web Page by Steven Hansen ---- Copyright 2010 - 2016 Econintersect LLC - all rights reserved