Navigation Links
First fruitful, then futile: Ammonites or the boon and bane of many offspring
Date:4/23/2012

For 300 million years, they were the ultimate survivors. They successfully negotiated three mass extinctions, only to die out eventually at the end of the Cretaceous along with the dinosaurs: Ammonoids, or ammonites as they are also known, were marine cephalopods believed to be related to today's squid and nautiloids. Ammonoids changed their reproductive strategy early on in the course of evolution. However, what was once a successful initial strategy may well have proved to be a fatal boomerang at the end of the Cretaceous, as an international team of researchers headed by paleontologists from the University of Zurich demonstrate in a study recently published in the science journal Evolution.

Embryos already had coiled shells

At the beginning of their evolution, ammonoids had straighter shells, which, like other mollusks, they began to coil during the Devonian Period. The precise reason behind this change is unknown. The selection pressure in favor of more tightly coiled shells is believed to have sprung from the ammonoids' natural predators. As the scientists have now discovered, the shell change also affected the ammonoid embryos. "In the oldest ammonoids, the embryonic shells were considerably bigger and coiled less tightly than in later forms," explains Kenneth De Baets, a paleontologist at the University of Zurich, summing up the latest findings.

Smaller hatchlings, more offspring

There were two more evolutionary trends that coincided with the increasingly more tightly coiled shells: The size of the embryonic shells shrank increasingly over time the hatchlings became smaller and smaller. In parallel, the shell size of fully grown animals increased and, on the whole, the animals became increasingly bigger. Based on this, the researchers deduced that the number of offspring in ammonoids rocketed during the Devonian Period. This is confirmed by discoveries of substantial clusters of fossilized embryonic shel
'/>"/>

Contact: Kenneth Da Baets
kenneth.debaeats@pim.uzh.ch
41-446-342-347
University of Zurich
Source:Eurekalert  

Page: 1 2

Related biology news :

1. Putting plants online: 4 leading botanical gardens to create first online catalog of all plants
2. ORNL microscopy yields first proof of ferroelectricity in simplest amino acid
3. First description of a triple DNA helix in a vacuum
4. Scientists complete first-ever emperor penguin count from space
5. First mass extinction linked to marine anoxia
6. New technology tracks sparrow migration for first time from California to Alaska
7. FirstMark Exhibiting at the Inaugural Atlanta Clinical Cardiology Update
8. FirstMark Announces New Hire Jay Houtman as Southeast Regional Sales Manager
9. First complete full genetic map of promising energy crop
10. Ottawa researchers to lead world-first clinical trial of stem cell therapy for septic shock
11. American College of Rheumatology releases first classification criteria for polymyalagia rheumatica
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
First fruitful, then futile: Ammonites or the boon and bane of many offspring
(Date:7/25/2014)... Boston, MA A study published online in the ... describes a novel approach to preventing cervical cancer based ... cervical cancer after removal of a discrete population of ... from a study that looked at squamocolumnar junction cells, ... canal and have been implicated as the origins of ...
(Date:7/25/2014)... University of Adelaide has opened the way for the development ... , In Australia, annual barley production is second only to ... one of the most important diseases of barley. , Senior ... composition of special growths on the cell walls of barley ... leaf. , The research, by the ARC Centre of Excellence ...
(Date:7/25/2014)... study shows that the age girls reach puberty is influenced ... on which parent contributes the gene. This is the ... development after birth and details of this study were published ... the first period, known as menarche, is a marker for ... that the onset of menses varies between girls, is an ...
Breaking Biology News(10 mins):Clearing cells to prevent cervical cancer 2New hope for powdery mildew resistant barley 2Could age of first period influence development of diseases in older women? 2
... controlling cell-membrane fat play a key role in turning off ... Chicago think so, and a biosensor they,ve created that measures ... treatment. Wonhwa Cho, distinguished professor of chemistry, and his ... act as sensors for lipid levels. Their findings are ...
... The genomic analysis technologies enable the study of genetic ... researches brought such a big and useful volume of ... published in Nature Genetics , promoted by the ... analysis and identifies three new chromosomal regions implicated in ...
... Secretary of the Interior Ken Salazar announced on October ... a consortium led by the University of Hawaii at Manoa, ... Guam. Together with two other new regional climate science centers, ... a network of eight regional centers being established by the ...
Cached Biology News:New membrane lipid measuring technique may help fight disease 2Genome-wide studies have identified new genes involved in susceptibility to melanoma 2University of Hawai'i chosen for new Climate Science Center 2University of Hawai'i chosen for new Climate Science Center 3
(Date:7/24/2014)... July 24, 2014 -- A novel combination of microscopy ... of Energy,s Oak Ridge National Laboratory an unprecedented look ... unusual physical and electrochemical properties. , The research ... affects the surface of a perovskite manganite, a complex ... new avenue to understand surface behavior could benefit researchers ...
(Date:7/24/2014)... on sophisticated equipment, trained personnel, and detection dogs ... terrorist attacks. A revolutionary new electronic chip with ... job much easier. , The groundbreaking nanotechnology-inspired sensor, ... University ,s School of Chemistry and Center for ... company Tracense, picks up the scent of explosives ...
(Date:7/24/2014)... Research and Markets has announced ... 2014-2018" report to their offering.  ... the in vitro growth of plant or animal cells ... biopharmaceutical production. Cell culture is a crucial step in ... cell culture consumables are necessary for the in vitro ...
(Date:7/24/2014)... 24, 2014 Three companies from the ... Livestrong’s Big C Competition. Out of 700 competition entrants, ... to the semi-final round. In this round twenty teams ... program, complete with mentoring from thought-leaders and medical entrepreneurs ... of the angelMD commitment to the Livestrong vision around ...
Breaking Biology Technology:ORNL study reveals new characteristics of complex oxide surfaces 2Nano-sized chip 'sniffs out' explosives far better than trained dogs 2Global Cell Culture Market 2014-2018: Key Vendors are Becton, Dickinson and Co, EMD, GE Healthcare, Lonza Group, Sigma Aldrich and Thermo Fisher Scientific 23 angelMD Startups Make Livestrong Big C Semi-finals 2
... around the Midwest looking for new ways to increase ... of bringing in developers to develop open lands and ... with tax incentives and reduced fees to relocate a ... common practice with even large municipalities in Chicago giving ...
... and consumer rights group believes the U.S. Supreme Court's ... Wisconsin Alumni Research Foundation regarding its stem cell ... its recent $1 million jury reward in the Xenon ... ,Representatives of the Foundation for Taxpayer and Consumer ...
... Boston, and youre on the verge of investing big bucks in ... team is in place, the business plan is tight, and the ... into the room, clears her throat and asks if youve ever ... check, she says, until you learn more about it. , ...
Cached Biology Technology:Electronic signs for municipalities: Las Vegas or lost revenues? 2Electronic signs for municipalities: Las Vegas or lost revenues? 3Electronic signs for municipalities: Las Vegas or lost revenues? 4California group says ruling weakens WARF's stem cell patent 2California group says ruling weakens WARF's stem cell patent 3California group says ruling weakens WARF's stem cell patent 4Why repealing the shareholder wage lien law makes sense 2Why repealing the shareholder wage lien law makes sense 3