The findings come from an analysis of 17 tyrannosaur fossils spanning a wide range of ages, from young juveniles to massive adults. Researchers say the work provides the most detailed reconstruction yet of how Tyrannosaurus grew throughout its life.

The study was published in the journal PeerJ.

Reading the Growth Rings Hidden Inside Dinosaur Bones

To estimate the age of dinosaurs, paleontologists often examine growth rings preserved inside fossilized bones. These rings are somewhat similar to the annual rings found in tree trunks. Each growth mark can provide clues about how quickly an animal was growing and how old it was when it died.

For decades, scientists have used these rings to reconstruct the life history of Tyrannosaurus rex. However, the new study employed more advanced techniques than earlier investigations. Researchers examined thin slices of fossil bone under specialized lighting that can reveal growth rings that are difficult to detect using standard methods.

The team also used sophisticated statistical models to combine information from multiple specimens. This allowed them to create a more complete picture of growth across the entire lifespan of T. rex.

The results indicate that Tyrannosaurus remained in a growth phase about 15 years longer than previously thought.

In addition, the findings suggest that some fossils traditionally assigned to T. rex may actually belong to other closely related species, or differ for other biological reasons.

Largest T. Rex Dataset Ever Assembled

“This is the largest data set ever assembled for Tyrannosaurus rex,” says Holly Woodward, a professor of anatomy at Oklahoma State University who led the research effort. “Examining the growth rings preserved in the fossilized bones allowed us to reconstruct the animals’ year-by-year growth histories.”

Unlike a tree stump, which preserves rings from an organism’s entire life, dinosaur bones provide only a partial record. A cross section of a T. rex leg bone typically preserves information from just the final 10 to 20 years of the animal’s life.

To overcome that limitation, the researchers combined growth records from multiple individuals of different ages.

“We came up with a new statistical approach that stitches together growth records from different specimens to estimate the growth trajectory of T. rex across all stages of life in greater detail than any previous study,” explains Nathan Myhrvold, a mathematician and paleobiologist at Intellectual Ventures who led the statistical analysis.

“The composite growth curve provides a much more realistic view of how Tyrannosaurus grew and how much they varied in size.”

A Slower Path to Becoming a Giant Predator

The new results paint a different picture of Tyrannosaurus development than earlier studies.

Instead of rapidly reaching adulthood, T. rex appears to have grown at a steadier pace over several decades. According to the researchers, this prolonged growth period may have helped younger tyrannosaurs occupy different ecological niches as they matured.

In ecology, a niche refers to the role an organism plays within its environment, including what it eats, where it lives, and how it interacts with other species.

“A four-decade growth phase may have allowed younger tyrannosaurs to fill a variety of ecological roles within their environments,” says coauthor Jack Horner of Chapman University. “That could be one factor that allowed them to dominate the end of the Cretaceous Period as apex carnivores.”

The Cretaceous Period ended about 66 million years ago, shortly before the extinction of non-avian dinosaurs.

Are Some Famous T. Rex Fossils Actually Different Species?

The study also contributes to an ongoing debate among paleontologists.

Although Tyrannosaurus rex is one of the most famous dinosaurs ever discovered, some researchers have argued that not every fossil labeled as T. rex necessarily belongs to the same species.

One controversial proposal suggests that several smaller fossils represent a separate dinosaur called Nanotyrannus rather than young Tyrannosaurus individuals. Other researchers have proposed that even some large specimens may belong to multiple closely related species.

The issue remains unresolved.

To investigate the question, the researchers included 17 fossils belonging to what they describe as the “Tyrannosaurus rex species complex,” a term acknowledging the possibility that more than one species or subspecies could be represented.

Two particularly famous specimens, nicknamed “Jane” and “Petey,” stood out from the rest. Their growth patterns differed significantly from those of the other fossils in the study.

While growth data alone cannot determine whether these animals belonged to different species, the unusual patterns make that possibility worthy of further investigation.

The researchers note that a separate recent study by Zanno and Napoli reached a similar conclusion using different methods, classifying Jane and Petey as two distinct species of Nanotyrannus.

Hidden Growth Rings Could Change Dinosaur Research

Another important finding involves the discovery of previously overlooked growth markers inside dinosaur bones.

Woodward, Myhrvold, and Horner found that circularly polarized and cross-polarized light can reveal a new type of growth ring. These hidden features may help explain discrepancies that have puzzled researchers studying dinosaur growth.

Because the approach is supported by strong statistical evidence, it could influence how scientists examine fossils in future studies, not only for T. rex but for many other dinosaur species as well.

“Interpreting multiple closely spaced growth marks is tricky,” Myhrvold says. “We found strong evidence that the protocols typically used in growth studies may need to be revised.”

A New Look at the Life of Tyrannosaurus Rex

More than a century after Tyrannosaurus rex was first described by scientists, the giant predator continues to reveal new surprises.

By combining a larger fossil sample, improved imaging techniques, and innovative statistical analysis, the new research provides one of the clearest views yet of how T. rex developed from a young dinosaur into one of the largest and most formidable land predators in Earth’s history.

The findings suggest that the king of dinosaurs may have taken far longer to grow up than anyone previously realized.

The work was led by teams from the CIBER Area for Diabetes and Associated Metabolic Diseases (CIBERDEM) at the University of Barcelona.

“Palmitic acid, a saturated fatty acid widely found in foods, is associated with impaired insulin sensitivity, whereas oleic acid, abundant in olive oil, may have a protective effect against these metabolic disorders,” says Professor Manuel Vázquez-Carrera, from the UB’s Faculty of Pharmacy and Food Sciences, the UB Institute of Biomedicine (IBUB), the Sant Joan de Déu Research Institute (IRSJD) and CIBERDEM.

Other contributors include Ricardo Rodríguez-Calvo of CIBERDEM at the Pere Virgili Institute for Health Research (IISPV), Marta Tajes of the CIBER Area for Cardiovascular Diseases (CIBERCV) at the Bellvitge Biomedical Research Institute (IDIBELL), and Walter Wahli of the University of Lausanne (Switzerland).

According to Vázquez-Carrera, the findings suggest that the type of fat people consume may be more important than the overall amount.

“This review highlights the significant role of the quality of dietary fat, rather than the total amount consumed,” notes Professor Manuel Vázquez-Carrera, who is a group leader at CIBERDEM at the UB.

How Palmitic Acid May Promote Diabetes

The researchers examined evidence showing that palmitic acid can trigger several biological processes linked to metabolic disease.

As Xavier Palomer (UB-IBUB-CIBER-IRSJD), the article’s first author, says, “at the molecular level, palmitic acid promotes the accumulation of potentially toxic bioactive lipids, fosters low-grade chronic inflammation, and contributes to the dysfunction of cellular organelles, such as the endoplasmic reticulum and the mitochondria.”

The team notes that these cellular changes “are closely linked to impaired insulin action and the progression of metabolic disease.”

Oleic Acid Shows Protective Effects

The picture looks quite different for oleic acid, a monounsaturated fat found in high amounts in olive oil.

According to the review, oleic acid encourages the body to store fats in forms that are metabolically less disruptive and have little effect on normal cellular function. It also helps maintain healthy insulin signaling in important metabolic tissues, including the liver, muscles, and adipose tissue.

Researchers say oleic acid may also offset many of the harmful effects associated with palmitic acid. This could help explain why eating patterns rich in monounsaturated fats, including the Mediterranean diet, are consistently linked to a lower risk of type 2 diabetes and other metabolic disorders.

Improving Nutrition Strategies for Diabetes Prevention

The authors emphasize that more targeted research is needed to better understand differences seen across population studies.

“It is important to consider variables such as the source of fatty acids, their dietary context, interactions with other nutrients, and different food processing methods,” says Manuel Vázquez-Carrera.

The researchers believe that gaining a clearer understanding of these factors will improve scientists’ ability to evaluate how different fats affect metabolic health. In turn, that knowledge could support the development of more effective dietary approaches for preventing and managing type 2 diabetes.

Our research has identified a link between those two developments, which means that trout, bass, perch and whitefish may become less common in unstocked lakes. But pike and walleye anglers may be in for a trophy-sized surprise.

In the past several decades, across much of northeastern North America and northern Europe, many freshwater ecosystems are getting darker, and they are changing in other ways as a result.

What is freshwater browning?

The specific phenomenon of darkening water, called “freshwater browning,” is driven by a few factors. Among the reasons are climate change, as higher temperatures and increased runoff are combining to increase the amount and types of carbon compounds that move from soil and land into bodies of water.

Similarly, as people have taken steps to reduce acidic emissions coming from smokestacks and other sources, less acid has fallen as precipitation, changing the chemistry of soils. Those chemical changes are also increasing the flow of carbon to bodies of water.

Higher levels of carbon make water look brown because it’s basically dissolved plant matter that stains the water like tea leaves would.

Underwater visibility

It’s harder to see in browner waters, which makes it harder for fish to locate prey, escape from predators and find suitable habitat to live in.

Our recent study combined a review of past research with some new analyses to examine how different kinds of fish do in darker water. Working with a large team of experts, we tallied findings from previous studies that looked at the relationship between the darkness of a body of water and fish growth rates in that same body of water.

We found that in browner waters, fish often grow more slowly. The decreased growth rate in individual fish appears to reduce the population sizes of these fish, which may, in turn, change the quantities and proportions of different kinds of fish in a lake.

But freshwater browning doesn’t affect all species of fish equally.

Unsurprisingly, we found that vision appeared to be quite important for navigating browner waters. When we studied fish communities in 303 Canadian lakes, we found that in lakes with darker water, fish species with larger eyes were more common.

When we looked at data on populations of eight economically important fish in 871 lakes across North America and Europe, we found that browning was associated with smaller populations of several species, including lake trout, lake whitefish, yellow perch, largemouth bass and smallmouth bass. Brook trout abundance was not affected by freshwater browning.

Browning was associated with larger populations of northern pike and walleye.

We believe that’s because walleye, for example, have a specialized retina that helps them see in browner waters with poorer visibility. Similarly, pike have a well-developed lateral-line sensory system that allows them to sense vibration, movement and pressure changes in the water.

A change for anglers

People fishing in browner lakes may consider appealing to the senses of the fish that are likely to be in the water. For example, rather than using colorful or shiny lures to attract their visual attention, when fishing in darker water, consider using vibrating lures that a fish’s lateral line system can detect, or scented lures that trigger an olfactory response.

By examining what’s happening to the water and in it, both scientists and people who enjoy fishing can understand the changes we’re seeing and what they mean in practical terms.

oth physical and mental abilities. However, new research from Yale University paints a far more optimistic picture. The study found that many older adults actually improve over time, and their beliefs about aging may play an important role in those gains.

Drawing on more than a decade of data from a large, nationally representative study of older Americans, researchers discovered that nearly half of adults age 65 and older experienced measurable improvements in cognitive function, physical function, or both.

The findings suggest that improvement in later life is far more common than many people realize.

“Many people equate aging with an inevitable and continuous loss of physical and cognitive abilities,” said Becca R. Levy, lead author of the study and professor of social and behavioral sciences at the Yale School of Public Health (YSPH). “What we found is that improvement in later life is not rare, it’s common, and it should be included in our understanding of the aging process.”

The study was published in the journal Geriatrics.

Aging and Improvement Over Time

The research team analyzed data from more than 11,000 participants in the Health and Retirement Study, a federally funded long-term survey of older Americans.

To measure changes in mental abilities, the researchers used a global cognitive assessment. Physical function was evaluated through walking speed, a measure often considered by geriatricians to be a key indicator of overall health because it is closely linked to disability, hospitalization, and mortality.

Participants were followed for as long as 12 years. During that period, 45% showed improvement in at least one of the two areas examined.

Approximately 32% improved cognitively, while 28% improved physically. Many participants experienced gains large enough to be considered clinically meaningful. When researchers also counted individuals whose cognitive abilities remained stable rather than declining, more than half of participants avoided the commonly held expectation of cognitive deterioration.

“What’s striking is that these gains disappear when you only look at averages,” said Levy, author of the book Breaking the Age Code: How Your Beliefs About Aging Determine How Long & How Well You Live. “If you average everyone together, you see decline. But when you look at individual trajectories, you uncover a very different story. A meaningful percentage of the older participants that we studied got better.”

The Role of Positive Age Beliefs

The researchers also explored why some older adults improved while others did not.

One possibility, they proposed, was the influence of age beliefs held at the beginning of the study. Specifically, they examined whether participants had adopted more positive or more negative views about aging.

Their analysis supported that idea. Older adults with more positive beliefs about aging were significantly more likely to improve in both cognitive performance and walking speed. The relationship remained strong even after adjusting for factors including age, sex, education, chronic disease, depression, and length of follow-up.

The findings build on Levy’s stereotype embodiment theory. The theory proposes that age-related stereotypes absorbed from society through sources such as social media and advertising can eventually become personally meaningful and have measurable biological effects.

Previous studies led by Levy found that negative beliefs about aging are associated with poorer memory, slower walking speed, increased cardiovascular risk, and biomarkers linked to Alzheimer’s disease.

According to Levy, the new findings show the opposite pattern can also occur.

The current study shows that those who have assimilated more positive age beliefs often show improvement, Levy said.

“Our findings suggest there is often a reserve capacity for improvement in later life,” she said. “And because age beliefs are modifiable, this opens the door to interventions at both the individual and societal level.”

Challenging Assumptions About Aging

The improvements were not limited to people who began the study with physical or cognitive impairments.

Researchers found that even participants who started with normal levels of cognitive and physical function frequently improved over time. This finding challenges the idea that later-life gains simply reflect recovery from illness or a return to previous levels after a setback.

The authors hope the results will help shift public perceptions about aging and reduce the belief that continuous decline is inevitable. They also suggest the findings support greater investment in preventive care, rehabilitation programs, and other health-promoting services that help older adults build on their capacity for resilience and improvement.

Martin Slade, a lecturer in occupational medicine at Yale School of Medicine and in the Department of Environmental Health Sciences at YSPH, co-authored the study.

The research was supported by funding from the National Institute on Aging.

A new study published in Nature has revealed an unexpected consequence of that process. Researchers from Kyoto University’s Institute for Integrated Cell-Material Sciences (WPI-iCeMS) and collaborating institutions found that migrating neurons routinely experience significant DNA damage. Specifically, the cells develop double-strand breaks, a severe form of DNA damage in which both strands of the DNA double helix are cut.

Although double-strand breaks are typically associated with mutations, cell dysfunction, and even cell death, the researchers discovered that they are a normal part of brain cortex development. In healthy brains, the damage is rapidly repaired before it can cause lasting problems.

“The developing brain appears to have evolved to tolerate and repair the neuronal damage efficiently,” says Professor Mineko Kengaku, of WPI-iCeMS, who led the study. “But understanding the limits of that tolerance — and what happens when repair is incomplete — brings us closer to understanding a range of neurological conditions.”

DNA Damage During Neuronal Migration

To investigate how this damage occurs, the researchers recreated the physical challenges faced by developing neurons. They guided neurons through tiny microchannels designed to mimic the confined spaces found in growing brain tissue.

Using fluorescent markers, the team observed double-strand DNA breaks appearing as neurons moved through the channels. Once the cells emerged from the other side, the damage gradually disappeared. Most of the breaks were repaired within 24 hours, and the neurons continued functioning normally.

The researchers identified the source of the damage as Topoisomerase IIβ, an enzyme that normally helps cells manage stress within DNA. Under ordinary conditions, the enzyme temporarily cuts DNA strands to relieve twisting and tension generated by routine cellular activity before reconnecting them.

The process can be compared to cutting a tangled cable to remove twists and then reconnecting it. However, when neurons are subjected to mechanical stress while squeezing through tight spaces, the enzyme can become trapped midway through the process, leaving sections of DNA broken. The cell then relies on a repair mechanism called non-homologous end joining to reconnect the damaged DNA ends.

Why Neurons Recover While Other Cells Do Not

The team found that neuronal DNA damage differs from the damage seen in certain cancer cells moving through the same microchannels. In cancer cells, DNA damage tends to occur more randomly and can disrupt normal cellular activity or trigger cell death.

In contrast, the DNA breaks in neurons were concentrated mainly in regions of the genome that are not actively involved in critical gene functions. Because essential genes are largely spared, the cells are able to maintain normal function despite the temporary damage.

When DNA Repair Falls Short

To explore the consequences of failed repair, the researchers engineered mice whose newly formed cerebellar neurons lacked Ligase 4, an enzyme required for repairing DNA breaks.

The mice developed normally and showed no obvious early abnormalities. However, as they reached adulthood, they began to experience mild but gradually worsening balance problems. These symptoms resemble those seen in certain human disorders linked to genome instability that affect the cerebellum.

Clues to Brain Diversity and Disease

The findings suggest that DNA breakage and repair may play a larger role in brain biology than previously recognized. Researchers now want to understand whether these early DNA changes contribute to differences between individual neurons and whether they influence neurodevelopmental or neurodegenerative diseases later in life.

“It shifts how we think about the neuronal genome,” says Professor Kengaku. “All neurons originate from the same DNA, but DNA damage and repair can introduce small genetic differences between individual neurons through a small mechanical journey. Some of that history may be written into the genome itself.”

The study was conducted through a collaboration involving Kyoto University, the University of Tokyo, the University of Osaka, the National University of Singapore, and the Tokyo Metropolitan Institute of Medical Science.