Tag Archives: swimming

Scientists confirm Spinosaurus was the only swimming dinosaur in history

Credit: Davide Bonadonna, University of Detroit Mercy.

Dinosaurs dominated the terrestrial environment for hundreds of millions of years, but air and water didn’t seem like their strong point at all. However, this shouldn’t be a cause for over-generalization. An international team of scientists has now confirmed that Spinosaurus aegyptiacus could swim, making it the first such dinosaur that we know of.

Spinosaurus is perhaps one of the most bizarre dinosaurs to have ever lived. It had the snout of a crocodile, a relatively large caudal fin on its back, and — as recent fossils have shown — a tadpole-like tail that was about as long as its body.

For decades, reconstructions of the dinosaur’s bulky body suggested that its tail was rather narrow and short. However, tail fossils belonging to Spinosaurus unearthed by paleontologists in Morocco suggest that the tail was larger and exhibited clear adaptations for aquatic environments.

Credit: arco Auditore/Gabriele Bindellini.

In fact, Spinosaurus had such a well-adapted tail that it resembles an oar when viewed from the profile. The end of the tail has no bony bumps, allowing the tip to undulate back and forth such that the dinosaur could propel itself forward through the water of river ecosystems.

“This was basically a dinosaur trying to build a fishtail,” Nizar Ibrahim, the lead researcher examining the fossil, told National Geographic.

Ibrahim had previously suggested that Spinosaurus was semi-aquatic in a 2014 study, but his evidence at the time wasn’t as convincing.

In addition to analyzing the structure and anatomy of the tail itself using photogrammetry, researchers at Harvard University also performed a robotic model of the tail’s movement, further cementing the notion that this dinosaur could swim, as reported in the journal Nature.

“This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm,” Ibrahim said. “This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water.”

However, Spinosaurus also spent time on land. How much time the 100-million-year-old dinosaur split between living in the water and in terrestrial environments is not clear at this point.

“These results are consistent with the suite of adaptations for an aquatic lifestyle and piscivorous diet that have previously been documented for Spinosaurus,” the researchers wrote in Nature.

All the bones of Spinosaurus used to describe the dinosaur in the new study are now housed at the University of Casablanca in Morocco. This is somewhat atypical but very welcomed for north-African research, as Moroccan fossils such as these often end up in collections at wealthy universities in Europe or the United States.

Three-quarters of swimmers suffer from ‘swimmer’s shoulder’

Credit: Pixabay.

“Swimmer’s shoulder’ is an umbrella term used to describe shoulder injuries suffered by both the swimming and general population. According to a new study, as many as three-quarters of competitive swimmers suffer from the painful overuse injury.

The shoulder is particularly vulnerable to injury due to its structure and complex biomechanics. The shoulder joint is made up of three important bones: the scapula (shoulder blade), clavicle (collar bone), and humerus (arm). There is a very small surface area where the bones articulate with each other, which means it is an inherently unstable joint.

Some swimmers might notice pain in the back of the shoulder after 25-30 minutes of swimming, while others may experience a sharper pinching feeling in the top of the shoulder at the same point in every stroke cycle. Similar symptoms might be incurred following an intense shoulder workout at the gym.

The researchers at Stanford University led by Eli Cahan surveyed 150 high school and youth club competitive swimmers aged 13-18, finding that 76.7% reported shoulder pain within the last 12 months.

When we perform a swimming stroke, the shoulder experiences a great deal of strain. Amateur swimmers typically have not much to worry since they don’t have to swim large over large distances on a daily basis like competitive swimmers.

Elite swimmers generally perform around 2,500 shoulder revolutions per day during their training sessions. The study found a strong association between distances swum and the incidence of shoulder pain. Those who reported no shoulder pain swam 1,568-3,513 yards (1,433-3,212 meters), whereas swimmers who experienced pain in their shoulder swam a median distance between 2,001-6,322 yards (1,829-5,780) per practice.

“Shoulder pain is significantly associated with median swimming distance but not with stroke type or specialized practice drills. To best tailor injury prevention programs for adolescent swimmers, programs must consider overall distance swum across strokes and drills rather than in specific scenarios alone,” the authors found.

Overtraining is also fostered by a “No pain, no gain!” culture. The study found that 66% of the surveyed competitive swimmers agreed with “mild shoulder pain should be tolerated” if they want to become successful swimmers and 61% that “taking time off from swimming is not ideal.” 

“This research showed that pain was normalized for both high school and club swimmers,” Cahan said in a press release. “Additionally, we found that nearly half of the athletes in our study know peers who use medication to address swim-related injuries, so we worry about the exposure to medications especially in the context of the opioid epidemic.”

Swim clubs were more associated with ‘swimmer’s shoulder’ than high school teams, the study also found.

“Both hold practices with similar frequency, but club practices are significantly longer in duration and length, the authors wrote in their study.

Sea snakes can dive up to 250 meters deep — that’s 800 feet

Snakes — they’re slithering on the ground, climbing trees, and now they’ve taken to the deep sea. A team of Australian researchers spotted two snakes swimming at depths of 239 and 245 meters, respectively — smashing the previous record by a whopping 133 meters.

Record-setting dive of a sea snake swimming at 240 meters in the deep-sea ‘twilight zone’ taken in July 2017. Image credit: INPEX-operated Ichthys LNG Project.

There are more than 3,000 snake species on Earth, and there’s at least one on every continent except Antarctica. They come in all sizes, ranging from a meager 10 centimeters to a whopping 10 meters (in the case of the reticulated python). They also inhabit an impressive array of habitats. Most live on the ground, but some are arboreal, and some even dwell around caves. There’s also a group of sea snakes.

Sea snakes are a highly venomous family inhabiting the warm coastal waters from the Indian Ocean to the Pacific. They dwell almost exclusively in water, and most of them are completely unable to move about on land. They’re excellent swimmers, being capable of swimming several kilometers in one go, and they also dive to search prey. However, they still need to breathe, and researchers thought they only dive to shallow depths. Until now.

“Sea snakes were thought to only dive between a maximum of 50 to 100 metres because they need to regularly swim to the sea surface to breathe air, so we were very surprised to find them so deep,” says Dr Jenna Crowe-Riddell, lead author of the study and recent PhD graduate at the University of Adelaide’s School of Biological Sciences.

The snakes were filmed in 2014 and 2017 using a remotely operated vehicle (ROV). The fact that there were two separate observations of two different species suggests this is not a freak occurrence, and sea snakes are quite capable of diving to these depths.

At depths of over 200 meters, things start to change dramatically. Very little light passes through to that depth, which is why this area, technically called the mesopelagic zone, is also referred to as the ‘marine twilight zone.’

Water pressure is also substantial at that depth, and for surface creatures to go that deep, you need very specific adaptations. The temperature is also quite low — which is quite challenging to cold-blooded creatures like snakes. This raises new questions about the thermal tolerance and overall ecologic capabilities of these snakes.

“We have known for a long time that sea snakes can cope with diving sickness known as ‘the bends’ using gas exchange through their skin,” says Dr Crowe-Riddell. “But I never suspected that this ability allows sea snakes to dive to deep-sea habitats.”

This also highlights the need to better understand these environments, which are at risk from climate change, ocean acidification, and human activity — better conservation first requires better understanding.

The study “First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200 m)” has been published in Austral Ecology. https://doi.org/10.1111/aec.12717