It’s turtle Tuesday! This loggerhead sea turtle was spotted in Flower Garden Banks National Marine Sanctuary. Loggerheads’ powerful jaws enable them to feed on hard-shelled prey, such as whelks and conch. Adults can reach up to 250 pounds!
Numerous groups of reptiles have “returned to the water” and become aquatic over the last three hundred million years, but tracing their direct ancestry can be surprisingly difficult. Highly modified and specialized anatomy, lack of transitional forms, and similar features convergently evolving multiple times can all obscure relationships, making it hard to properly classify them.
We’re only just starting to figure out the true origin of turtles (they’re probably archosauromorphs), and they’re a marine reptile group with living members.
Some of the extinct ones are even more uncertain. For example: mosasaurs. (Represented here by the eponymous Mosasaurus.)
While some semi-aquatic early mosasaurs are known, and they seem to be closely related to aigialosaurs and dolichosaurs, their exact placement within the squamates is a lot less clear. Traditionally they were regarded as the sister group to snakes, but some studies have found them to be closer to monitor lizards instead, and others have even placed them as much more basal scleroglossans. Their classification in phylogenetic analyses is “highly unstable”, changing depending on what other reptile groups are included, so there’s no real current consensus.
(And even if they are most closely related to snakes, that doesn’t necessarily help much – the exact origin and evolution of snakes is still very poorly known, too!)
New personal piece! Tough to find the time to work on this, so its been short painting sessions here and there over the last month. I got to apply a lot of new things I’ve been learning in school here and it was a fun painting!
When Charles Darwin was off observing wildlife in the Galápagos Islands, he wasn’t just looking at finches. In fact, one of the most striking creatures that Darwin found was the Marine Iguana (Amblyrhynchus cristatus). To Darwin, this species was strikingly…stupid.
Marine Iguanas are necessarily dumb, but when Darwin and his fellow shipmates reached the Galápagos, the iguana species was so far removed from human contact that it didn’t consider them a threat. One of my favorite Darwin anecdotes is about the famed naturalist repeatedly throwing a single iguana into the ocean, only to have it swim right back to rest in the same place.
These are huge, huge lizards, reaching over a meter in length, so the idea of one being tossed into the sea is a bit of a strange one. It really does make one wonder what other animal species might be like without the constant threat of predation or disturbance.
This large male Green sea turtle came into the reef for a much needed clean. I took a couple photos and then just sat with it for ten minutes as it got cleaned. It must have been at sea for a long time to be this dirty, or maybe it keeps getting creeped out by people staring at him every time he tries to get cleaned. It was such an old turtle, I cried I was so happy to share a moment with such an amazing creature. Currently listed as Endangered by the IUCN Red list.
The group called dinosaurs includes all the animals that evolved from the very first dinosaur, the common ancestor. Because the fossil record is incomplete, we have not found fossils of this common ancestor; however, based on the characteristics we see in all dinosaurs, we can determine new and unique characteristics it possessed.
A key evolutionary innovation of dinosaurs is that they walk with a fully erect posture, holding their hind legs vertically under their hips. The top of the thighbone (or femur) has a knob or head that sticks out to the side of the rest of the bone and fits into the hip socket (or acetabulum) in the pelvis. The hip socket has a hole in the center, as well as a rim of bone along the upper margin, which helps support the weight of the body on the leg. Since these features are present in all known dinosaurs, we deduce that they first evolved in the common ancestor.
In popular culture, many other kinds of animals, which don’t have this fully developed hip and leg structure, are often incorrectly called dinosaurs. Some examples include Mesozoic marine reptiles, such as plesiosaurs, mosasaurs and ichthyosaurs, as well as a group of Mesozoic flying reptiles called pterosaurs.
This video is part of a series, “Dinosaurs Explained,” produced by the American Museum of Natural History. In the series, Museum paleontologists answer the most frequently asked questions about dinosaurs.
Mosasaurs are an infamous group of marine lizards. Thought to be closely related to snakes and monitor lizards, mosasaurs are long, streamlined, and well-adapted for an aquatic existence, with paddle-shaped limbs and fluked tails. Mosasaurus is the biggest of the lot; some fossil specimens can reach an excess of 50 feet! Big Blue is currently 30 feet - which is still a good size. Mosasaurs are active warm-blooded predators, known to prey on fish and other marine reptiles. As well as the many conical teeth that line the dental margins of the mouth, they have a second row of teeth on the palate, useful for dragging prey further into the throat. Mosasaurus itself is especially robust. Discovered in 1764, it’s become among the most infamous marine reptiles, mostly due to being so big.
Take the stairs down from the aquarium’s Western Interior Seaway hall to the viewing room to see the Trench of the Mosasaur. Gaze into the massive sea pen we’ve built for her, suitable for an animal of her size. On weekday mornings, you can hop on a boat and watch us feed her deep in the sea pen.
Mosasaurs have a good sense of hearing, and especially tune into repetitive low-frequency sounds (like the sounds of splashing prey). We found that hard rock music is quite effective at drawing her to the boat for feeding, better than the scent of chum even! Recommend songs for Big Blue’s Spotify playlist in our Ask box. We’re always looking to keep her interested in the latest in hard rock fads!
Personality & History
Big Blue is our second mosasaur ever produced by our facility’s geneticists. She bears genome version 1.0, as version 0.9′s mosasaur had passed during artificial gestation. The successful birth of a large marine predator brought an extensive set of architectural and procedural development for our aquarium. She was at first raised in a tank in the Western Interior Seaway hall, part of which is now occupied by our Eonatator. Knowing that she’d outgrow the facility, consultants from the now-defunct Free Willy-Keiko Foundation were flown in to oversee her care as a juvenile and the construction of a much bigger abode.
At 5m, we introduced her into her permanent home: a custom-built sea pen with hydrophone deterrents to dissuade her from venturing close to the thick mesh walls. She’s acclimated quite well, giving us hope for when our megatooth sharks graduate to a full sea pen.
Big Blue is quite inquisitive, often displaying interest in visitors when she swings by the underwater viewing window. If she bumps a viewing boat, consider it a friendly nudge. She has yet to attack a human-navigated vessel, preferring big smelly hunks of meat over cold hard metal - but the boats have a scent-based repellent as well as a number of trade-secret deterrents to stymie her curiosity.
She is not without her own set of challenges that the Huxley keepers & aquarists must keep careful attention to! Big Blue is prone to an undescribed genus of Australian marine parasite (similar to sea lice, our taxonomists have found) that cause her superficial injuries to the skin and tongue. After calling her into a shallow, protected medical pool, a specialized dive team descend and carefully remove any “mosasaur lice” found from our custom bio-scanners. The dedicated 8-person team have earned her affection. Er. As much as a mosasaur can display affection, rather. Toleration might be a better word for it.
We promise it’s nothing to worry about! Our vets are working on a topical remedy as well as the possibility of introducing a larger stock of live fish into the pen to combat the population of these little buggers.