Nav: Home

Crocodiles have complex past

January 24, 2019

A new study throws into question the notion that today's crocodiles and alligators have a simple evolutionary past.

Previous research has pointed to crocodiles and alligators starting with a land-based ancestor some 200 million years ago and then moving to fresh water, becoming the semi-aquatic ambush predators they are today.

But a new analysis, published online today in the journal Scientific Reports, offers a different story. Modern crocodiles and alligators came from a variety of surroundings beginning in the early Jurassic Period, and various species occupied a host of ecosystems over time, including land, estuarine, freshwater and marine.

As University of Iowa researcher and study co-author Christopher Brochu says, "Crocodiles are not living fossils. Transitions between land, sea, and freshwater were more frequent than we thought, and the transitions were not always land-to-freshwater or freshwater-to-marine."

Brochu and colleagues from Stony Brook University pieced together crocodile and alligator ancestry by analyzing a large family tree showing the evolutionary history of living and extinct crocodylomorphs (modern crocodiles and alligators and their extinct relatives). The team was then able to predict the ancestral habitat for several divergence points on the evolutionary tree.

This suggests a complex evolutionary history not only of habitat, but of form. Those living at sea had paddles instead of limbs, and those on land often had hoof-like claws and long legs. These did not all evolve from ancestors that looked like modern crocodiles, as has long been assumed.

The paper is titled, "Evolutionary structure and timing of major habitat shifts in Crocodylomorpha."

Study co-authors are Eric Wilberg and Alan Turner, from Stony Brook University.

The U.S. National Science Foundation funded the research, through grants to each author.
-end-


University of Iowa

Related Ecosystems Articles:

Viruses as modulators of interactions in marine ecosystems
Viruses are mainly known as pathogens - often causing death.
How to prevent mosquitofish from spreading in water ecosystems
Preventing the introduction of the mosquitofish and removing its population are the most effective actions to control the dispersal of this exotic fish in ponds and lakes, according to a study published in the journal Science of the Total Environment.
Mount Kilimanjaro: Ecosystems in global change
Land use in tropical mountain regions leads to considerable changes of biodiversity and ecological functions.
The fiddlers influencing mangrove ecosystems
The types of bacteria living in and around fiddler crab burrows vary widely between mangroves, but their functional activities are remarkably similar.
Improving ecosystems with aquatic plants
Wetland restoration is critical for improving ecosystem services, but many aquatic plant nurseries do not have facilities similar to those typically used for large-scale plant production.
Pollution in cities damaging insects and ecosystems
High levels of pollution found in many of the world's major cities are having negative effects on plants and insects, according to new research from the University of Sheffield.
Biodiversity can also destabilize ecosystems
According to the prevailing opinion, species-rich ecosystems are more stable against environmental disruptions such as drought, hot spells or pesticides.
Alpine ecosystems struggle to recover from nitrogen deposition
A new CU research study finds that degraded alpine ecosystems showed limited recovery years after long-term inputs of human-caused nitrogen air pollution, with soil acidification and effects on biodiversity lingering even after a decade of much lower nitrogen input levels.
Ecosystems are getting greener in the Arctic
Researchers from Berkeley Lab have developed a new benchmark model that estimates changes in the proportion of the Earth's surface where plant growth will no longer be limited by cold temperatures over the 21st century.
No refuge in the deep for shallow reef ecosystems
Deep water coral reefs are not the places of refuge for shallow reef organisms that some scientists have considered them to be, a new report suggests.
More Ecosystems News and Ecosystems Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#540 Specialize? Or Generalize?
Ever been called a "jack of all trades, master of none"? The world loves to elevate specialists, people who drill deep into a single topic. Those people are great. But there's a place for generalists too, argues David Epstein. Jacks of all trades are often more successful than specialists. And he's got science to back it up. We talk with Epstein about his latest book, "Range: Why Generalists Triumph in a Specialized World".
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.