PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Ancient sharks reared young in prehistoric river-delta nursery

2014-01-07
(Press-News.org) Contact information: Jim Erickson
ericksn@umich.edu
734-647-1842
University of Michigan
Ancient sharks reared young in prehistoric river-delta nursery ANN ARBOR—Like salmon in reverse, long-snouted Bandringa sharks migrated downstream from freshwater swamps to a tropical coastline to spawn 310 million years ago, leaving behind fossil evidence of one of the earliest known shark nurseries.

That's the surprising conclusion of University of Michigan paleontologist Lauren Sallan and a University of Chicago colleague, who reanalyzed all known specimens of Bandringa, a bottom-feeding predator that lived in an ancient river delta system that spanned what is today the Upper Midwest.

The new findings, scheduled for online publication Jan. 7 in the Journal of Vertebrate Paleontology, mark the earliest known example of shark migration—a behavior that persists today among species such as tiger sharks in Hawaii.

The Bandringa fossils, as reinterpreted by Sallan and Michael Coates, also reveal the only known example of a freshwater to saltwater shark migration, as well as the earliest example of a shark nursery where fossilized egg cases and juvenile sharks were preserved in the same sediments.

"This pushes migratory behavior in sharks way back," said Sallan, an assistant professor in the U-M Department of Ecology and Evolutionary Biology. "These sharks bred in the open ocean and spent the rest of their lives in fresh water. No shark alive today is known to do that."

The long-extinct Bandringa is likely one of the earliest close relatives of modern sharks. It resembled present-day sawfish and paddlefish, with a spoon-billed snout up to half its body length. Juveniles were 4 to 6 inches long and grew into adults of up to 10 feet.

Bandringa was discovered in 1969 and soon became one of the most prized fossils from the well-known Mazon Creek deposits in northern Illinois. Until now, researchers believed that the genus Bandringa contained two species, one that lived in freshwater swamps and rivers and another that lived in the shallow ocean.

But after reevaluating fossils from 24 individuals, including latex "peels" of Bandringa's scale-covered skin, Sallan and Coates concluded that Bandringa was a single species that lived, at various times during its life, in fresh, brackish and salt water.

The physical differences between the two purported species were due to different preservation processes at marine and freshwater locations, Sallan and Coates concluded. The freshwater sites tended to preserve bones and cartilage, while the marine sites preserved soft tissue.

By combining the complementary data sets from both types of fossil sites and reclassifying Bandringa as a single species, Sallan and Coates gained a far more complete picture of the extinct shark's anatomy and discovered several previously unreported features. They include downward-directed jaws ideal for suction-feeding off the bottom, needle-like spines on the head and cheeks, and a complex array of sensory organs (electroreceptors and mechanoreceptors) on both the extended snout and body, suited for detecting prey in murky water.

Adult Bandringa sharks lived exclusively in freshwater swamps and rivers, according to Sallan and Coates. Females apparently traveled downstream to a tropical coastline to lay their eggs in shallow marine waters, a reverse version of the modern-day salmon's sea-to-stream migration. At the time, the coastline of the super-continent Pangaea ran diagonally between the Mazon Creek freshwater and marine sites.

All the Bandringa fossils from the Mazon Creek marine sites are juveniles, and they were found alongside egg cases—protective capsules that enclose eggs of the next generation—belonging to an early species of shark. Adult Bandringa fossils have been found only at freshwater locations, including several in Ohio and Pennsylvania.

Sallan and Coates said that the juvenile Bandringa sharks hatched from the Mazon Creek egg cases, and that the deposit's marine sites represent a shark nursery where females spawned and then departed, returning upstream to freshwater rivers and swamps.

"This is the first fossil evidence for a shark nursery that's based on both egg cases and the babies themselves," Sallan said. "It's also the earliest evidence for segregation, meaning that juveniles and adults were living in different locations, which implies migration into and out of these nursery waters."

The Mazon Creek deposit is known for its extremely diverse, well-preserved fossils, with more than 320 animal species identified, according to the Illinois State Museum.

Many of those animals lived in shallow marine bays. Other plants and animals lived in swampy areas along rivers that emptied into the bay. When the remains of all these plants and animals sank to the bottom of the bay, they were rapidly buried by mud washing in from the river, which preserved them.

### Financial support for the project was provided by the National Science Foundation, the University of Chicago, the University of Michigan and the Michigan Society of Fellows.


ELSE PRESS RELEASES FROM THIS DATE:

How you practice matters for learning a skill quickly

2014-01-07
How you practice matters for learning a skill quickly Practice alone doesn't make perfect, but learning can be optimized if you practice in the right way, according to new research based on online gaming data from more than 850,000 people. The ...

Ants shape their thoraces to match the tasks they perform

2014-01-07
Ants shape their thoraces to match the tasks they perform This news release is available in Portuguese. It was now discovered that the specialization of queen and worker ants goes beyond the presence or absence of wings. In a study published ...

Racism may accelerate aging in African-American men

2014-01-07
Racism may accelerate aging in African-American men UMD-led study is first to link racism-related factors and cellular age A new study reveals that racism may impact aging at the cellular level. Researchers found signs of accelerated aging in African American men, ages reporting ...

NYSCF scientists make living brain cells from Alzheimer's patients biobanked brain tissue

2014-01-07
NYSCF scientists make living brain cells from Alzheimer's patients biobanked brain tissue New study shows ability to make living human cells from biobanked brain tissue NEW YORK, NY (January 7, 2014) – Scientists at The New York Stem Cell Foundation (NYSCF) Research ...

Some brain regions retain enhanced ability to make new connections

2014-01-07
Some brain regions retain enhanced ability to make new connections In adults, some brain regions retain a "childlike" ability to establish new connections, potentially contributing to our ability to learn new skills and form new memories as we age, ...

Several forms of vitamin E protect against memory disorders

2014-01-07
Several forms of vitamin E protect against memory disorders Elderly people with high serum vitamin E levels are less likely to suffer from memory disorders than their peers with lower levels, according to a study published recently in Experimental ...

Patterns of social interaction remain consistent over time

2014-01-07
Patterns of social interaction remain consistent over time The research was conducted by researchers form Aalto University and University of Oxford, and was published in Proceedings of the National Academy of Sciences of the United States of America (PNAS) recently. "We ...

The power of packaging in consumer choices

2014-01-07
The power of packaging in consumer choices Researchers from the University of Miami and California Institute of Technology show how the brain considers both visual cues and taste preferences when making everyday food choices CORAL GABLES, FL (January 6, 2014) — ...

By the numbers: A simple 10 step approach to reducing the harms of alcohol

2014-01-07
By the numbers: A simple 10 step approach to reducing the harms of alcohol London, LA (07 January 2013). Much the same way individuals are encouraged to know their blood pressure and cholesterol numbers to maintain a healthy lifestyle, a new editorial in the Journal ...

Low diversity of bacteria may increase the risk for asthma

2014-01-07
Low diversity of bacteria may increase the risk for asthma Low gut microbial diversity in the intestines of infants can increase the risk for asthma development. These are the findings of the age 7 follow-up in a multi-year study led by researchers at ...

LAST 30 PRESS RELEASES:

U of I researchers trace genetic code’s origins to early protein structures

Disease experts team up with Florida Museum of Natural History to create a forecast for West Nile virus

Researchers: Targeted efforts needed to stem fentanyl crisis

New UMaine research could help lower prescription drug costs

Molecular movie shows how mitochondria read their DNA

Loss of key male fertility gene leads to changes in expression of hundreds of other genes

Water’s density is key to sustainable lithium mining

Pioneering research reveals problem gambling quadruples the risk of suicide among young people four years later

New method improves the accuracy of machine-learned potentials for simulating catalysts

Astronomers discover rare Einstein cross with fifth image, revealing hidden dark matter

UCalgary researchers show brain shunts significantly benefit older adults with hydrocephalus

UCalgary researchers pursue new approach to manage deadly lung scarring

Psychotherapy can be readily integrated into brief “med-check” psychiatry visits

‘Wiggling’ atoms may lead to smaller, more efficient electronics

Alliance webinar highlights latest advances in cancer treatment

Climate change could drastically reduce aquifer recharge in Brazil

$1.7M DOD grant funds virtual cancer center to support research into military health

Brain organoids could unlock energy-efficient AI

AI-powered CRISPR could lead to faster gene therapies, Stanford Medicine study finds

Shared genetic mechanisms underpin social life in bees and humans

Prescribed opioid pain medications during pregnancy likely aren’t associated with increased risk of autism, ADHD

Sustainable, plant-based diet benefits both human and planetary health

IU researchers find that opioid pain meds prescribed during pregnancy do not cause increased risk of autism or ADHD

Holocaust testimony is AI litmus test, and it fails

Preventing corruption in the lymph nodes

Older adults with hydrocephalus benefit from shunt surgery

Strong-confinement low-index-rib-loaded waveguide structure for etchless thin-film integrated photonics

Kidney transplant rejection associated with changes in lymphatic vessels, new research shows

EWRR becomes an official EULAR Congress

How HIV enters the genome – Researchers identify previously unknown mechanism

[Press-News.org] Ancient sharks reared young in prehistoric river-delta nursery