Sirens are part of the salamander branch of the lissamphibians, and are some of the most unusual members of the group. They have an eel-like body shape, with small forelimbs and no hindlimbs at all, and have functional external gills as adults. Their main diet is carnivorous, with palatal teeth and a keratinous beak at the front of their jaws adapted for eating hard-shelled prey – but they’ve also been observed feeding on plant material, a rarity among amphibians.

Habrosaurus here was one of the earliest known sirens, living during the Late Cretaceous and Early Paleocene of North America (~84-58 mya). Reaching lengths of around 1.6m (5′3″), it was one of the largest known lissamphibians of all time, comparable in size to some modern giant salamanders.

It lacked the beak seen in its modern relatives, instead having specialized chisel-like teeth at the edges of its jaws that convergently served the same purpose of delivering a crushing bite.


Teleocrater rhadinus from the Middle Triassic (~245 mya) of Tanzania. Measuring about 2.5m long (8′2″), it was one of the earliest known members of the avemetatarsalians – the dinosaur-and-pterosaur (or “bird-line”) branch of the archosaurs. Its fossils have been known for over 80 years, but it was only very recently given an official name and classification following the discovery of additional specimens in 2015.

It turned out to be rather different from what paleontologists had expected an early bird-line archosaur to look like. Instead of being a bipedal basal-dinosaur-like animal, Teleocrater was actually a quadruped with more crocodilian-like limbs and oddly elongated neck vertebrae.

I’ve done two variations of the image today – both with and without a little speculative proto-fuzz.

An illustration of an extinct reptile related to the ancestors of dinosaurs and pterosaurs. It's a quadrupedal animal with a lizard-like head, a long neck, crocodile-like limbs, and a long tail.
Teleocrater rhadinus (no fuzz version)


Globicetus hiberus, a 5m long (16′4″) beaked whale from the Atlantic coast of Portugal and Spain. Its fossils can’t be easily dated since they were fished up from the seafloor, but it was probably around Early-to-Mid Miocene in age (~20-14 mya).

Its skull sported an odd bony sphere at the base of its snout, just in front of the melon, which appears to have been larger and more prominent in males than in females. Many modern beaked whales also have sexually dimorphic crests, ridges, and domes in their skulls, and these structures may function as sort of “internal antlers” – a display structure the whales can “see” via echolocation that signals their size, strength, and health to each other.


Utahraptor ostrommaysorum lived during the Early Cretaceous (~130-124 mya) in Utah, USA, and was the largest known dromaeosaurid. Reaching lengths of around 6m long (20′), it’s often compared in size to the fictional raptors of Jurassic Park.

Recent discoveries show it had some weird proportions compared to its relatives – a thick stocky body, chunky legs, smaller arms, a shorter and more flexible tail, and a large deep skull with an oddly curved lower jaw.

But we still don’t know very much about it… yet.

There’s a huge slab of rock full of Utahraptor fossils just waiting to be extracted and studied. There are at least six raptors in there ranging from babies to adults, hinting at the presence of a family group or even pack hunting behavior, and potentially other animals and new discoveries too – but the main roadblock for this project is lack of funding.

The paleontologists involved have turned to crowdfunding to attempt to raise enough money for essential equipment and the services of a professional fossil preparator, but they’re still only at about 10% of their goal.

So this first week of April is #UtahraptorWeek in the paleontology community, raising awareness of this fascinating giant raptor and how close we are to finding out so much more about it. Spread the word, and if you’re able to please consider helping out the Utahraptor Project on GoFundMe.