Taxon of the week: Euphanerops

Having been treated to a dinosaur last time in taxon of the week, this week I’ve decided to go for an obscure Palaeozoic fish.  This fish is pretty obscure even for a Palaeozoic fish; so obscure, in fact, that it doesn’t even have its own Wikipedia article.  I speak, as you’ll know if you bothered to follow that link, of the Devonian jawless fish Euphanerops.

Screen Shot 2014-03-06 at 09.50.15

Euphanerops in all its fossilised glory (Sansom et al, 2013)

Loathe as I am to introduce even more palaeontological nudity to The Dinosirs, Euphanerops is a so-called ‘naked anaspid’, a group that look similar, but not the same, as modern lampreys.  The naked anaspids consist of a handful of taxa that are united by the fact that they look a bit like members of a larger group, the anaspids, but don’t have their distinctive bony scales.  Both groups look like they lie somewhere on the gnathostome stem-lineage, which we met when we looked at heterostracans a few weeks ago.  As we saw then, these stem-gnathostome groups are extremely important in understanding vertebrate evolution as they provide our only morphological information on how characters like jaws and paired fins evolved in vertebrates. Euphanerops

A lamprey-like reconstruction of Euphanerops. Ten points if you can spot the mistake before getting to the end of the post. (From

The specific area onto which Euphanerops sheds light is the evolution of paired fins.  Jawed vertebrates today all possess paired fins, whether as traditional ‘fins’ or as limbs in tetrapods (although some, like snakes, have secondarily lost them).  Modern jawless vertebrates, the lampreys and the hagfish, have no paired fins, they have only single ‘median’ fins down their midline.  Unfortunately this gives us no information regarding how paired fins evolved, for all we know they may have just popped into existence.  One avenue of investigation in solving the puzzle is evolutionary developmental studies (evo-devo), where the development of modern animals is studied for clues.  This gives us intriguing hints, for example paired fins seem to develop in similar ways to both gill arches and median fins, suggesting a possible shared evolutionary origin.  They can also be induced to develop along a lateral line along the sides of the body.   However, if we want to know how the structure changed morphologically we have but one recourse.  To the fossil record!


A cartoon phylogeny of vertebrates with handy colour-coded fins. Green for dorsal fins, blue for anal fins and red for paired fins. Mixes arise from combinations (from Sansom et al, 2013).

Fossils clear up the picture quite a lot.  The earliest ‘paired fins’ we see are in groups like the thelodonts and the (clothed) anaspids, but these are all paired ‘fin-folds’, fin-like structures that lie paired along the body in vaguely the same place as pectoral fins, but which have no skeleton supporting them. Some heterostracans, such as Pteraspisalso have bony paired fin-like projections from their head-shields, but it looks like these are just convergent adaptations rather than actually being fins. Osteostracans, a group with a wide array of fancy head shields, have the first paired fins as we know them today, with a skeleton on the inside (like your limb bones).  They only had pectoral paired fins (ie. the front fins of a fish, or your arms), and the skeleton was made of cartilage, but they were paired fins nonetheless, although some groups of osteostracan secondarily lost them again.  Later, in jawed groups such as the placoderms, we finally see the full complement, of pectoral and pelvic paired fins.

anaspid fin folds wikipedia

Anaspids (of the clothed variety) with fin-folds coloured in green (from Wikipedia).

Combined with the molecular evidence this progression from no paired fins to paired fin-folds to paired fins with skeleton has been used to propose an evolutionary mechanism.  The story runs that lampreys and hagfish have a single stripe of ‘fin-competency’ down their midline, where fins can develop.  This stripe was somehow double and spread onto the sides of groups such as anaspids, allowing paired fin-folds to develop on the sides as well.  These paired ‘fin-competency’ zones then began to interact with the developmental tissue that bone is formed from, leading to skeletonisation of the fin in later groups, and eventually to the complex fin skeletons we see today.


This figure shows the proposed spread of a line of ‘fin-competency’ first from the midline onto the flanks to create ‘fin-flaps’ in various places, and then interacting with other developmental tissues to create the familiar skeletonised fins we see today at the bottom (from Yonei-Tamura et al, 2008)

This seems like a good explanation, and fits the evidence well.  Euphanerops makes the picture a bit more complicated however.  The genus has been known for a long time, and is also interesting in that some fossils appear to preserve a lamprey-like gill skeleton, which would imply that this is ancestral for gnathostomes.  Our interests lie however in the realm of paired fins, and in 2013, a fossil was described as having paired fins.  In itself this is not unusual, as the similar anaspids sometimes have paired fins in a position roughly where pectoral fins are in modern fish.  Euphanerops however has paired fins where the anal fin is in a modern fish, ie. between the anus and the tail.  This state of affairs is not known in any modern fish, or in any other extinct ones we know of.

Paired fin comparison

The paired anal fins of Euphanerops fossilised above and outline below (from Sansom et al, 2013)

This has interesting implications for the evolution of paired fins.  It seems that rather than just following a progression from no fins to paired fins, evolution had a period of ‘experimentation’ with paired fins in different places before settling on the paired fins we see today.  This fits in with our overall picture of evolution: while it can be tempting to think that it ‘progresses’ towards an aim, in fact it occurs piecemeal, leaving behind a mosaic of different ‘experiments’ with morphologies.  It’s also worth noting that lines of fin competency idea of fin evolution mentioned before isn’t overturned by Euphanerops and its paired fins, but our picture of paired fin evolution is broadened.

Screen Shot 2014-03-06 at 09.49.35

Euphanerops restored with paired anal fins! (Sansom et al 2013)

So, far from being merely an unclothed anaspid and a Twitter handle that rolls off the tongue, Euphanerops and its paired fins have much to tell us about both paired fin evolution and wider evolutionary principles.  Like Limusaurus last week it also illustrates how palaeontological and molecular methods can be used in a synthesis to better understand evolution.   Pretty impressive all round for a fish that not even Wikipedia loves*.

*But I love you Euphanerops!.



Sansom et al (2013) Unusual anal fin in a Devonian jawless vertebrate reveals complex origins of paired appendages.

Janvier et al (2006) Lamprey-like gills in a gnathostome-related Devonian jawless vertebrate.

Yonei-Tamura et al (2008) Competent stripes for diverse positions of limbs/fins in gnathostome embryos.

Johansen (2010) Evolution of paired fins and the lateral somatic frontier.



What’s new/s 03/03/14

What’s news has been neglected a bit over the last few weeks, but fear not! Here are five exciting palaeo news stories from the last month or so:

Placoderm faces

For no particularly good reason, placoderms are a group close to my heart.  This group of fish existed during the Devonian, and are the earliest example of vertebrate with jaws in the fossil record,  As well as being generally awesome, they are also crucial to understanding how gnathostomes, the jawed vertebrates, evolved from their jawless ancestors.  Dupret et al have CT imaged a primitive placoderm, Romundina, and have shown that it has a mixture of jawless fish (‘agnathan’) and gnathostome  cranial  characters.  As with so much of evolution, the transition to attaining jaws seems to have been piecemeal, part by part, an example of mosaic evolution, with cerebral proportions remaining largely unchanged with the evolution of jaws.


Romundina in all its glory. This is the head with front end to the left, the large, round holes are the orbits. (from

Even more Burgess Shale

The Cambrian is famous for the weird and wonderful fossil taxa that existed during it, and the most famous Cambrian fossil site is the Burgess Shale, in the Canadian Rockies.  Since the early 20th century the incredible preservation of this site has given us an invaluable window into life 500 million years ago.  While the Burgess Shale animals were famously argued by Stephen Jay Gould to represent experimentations in body plans alien to anything alive today, more recent work has shown that actually these animals are early relatives of groups such as arthropods (ie. insects, crustaceans etc) and vertebrates (ie. you).  The other week another site was described from the Burgess Shale; hopefully this will mean we’ll see lots of new Cambrian beasties over the next few years, as well as more information on known ones,  continuing to fill in our picture of early animal evolution.


A range of weird and wonderful Cambrian fossils from the new assemblage. (from Caron et al)

Aquatic Acanthostega

We already met Acanthostega, the earliest known tetrapod, a few weeks ago, when we were looking at Tiktaalik and the transition of vertebrates onto land.   Acanthostega possesses a mixture of aquatic and terrestrial qualities: like a fish, it has gills and a tail fin, but like a modern tetrapod it had digits and a ‘neck’ between the head and body.  This has been taken to demonstrate that tetrapods actually evolve many ‘adaptations to land’, such as digits, while the still lived in water, in contrast to the historical view that a (presumably rather optimistic) fish crawled onto land and only then adapted to it. Recent work by Neenan et al suggests that Acanthostega’s jaw was adapted to aquatic, rather than terrestrial, feeding, which they argue refutes recent suggestions that it might have fed on land, or at least above water.

Optimistic fish

An optimistic fish (from

Playing around with flight

Imagine, if you will, a bird.  Chances are that you’re imagining something that’s probably feathered and beaked*.  The fossil record, however, shows us that many traits that we associate with birds, such as feathers and beaks, evolved before birds came into existence as a group.  Feathers are perhaps the best example, found in many dinosaurs not particularly closely related to birds, but it is also true of various skeletal characters.  Work by Mark Puttick and others shows that this is the case with the comparatively long forelimbs of birds, which originated before the origins of the group, amongst earlier dinosaurs.  Gliding dinosaurs like Microraptor suggest that many groups were independently evolutionarily ‘playing around’ with feathered gliding, it was just the birds that happened to evolve powered flight and make it through to today.

*If not, you may want to double check that you know what a bird is.


Microraptor: Evolutionary experimentation with flight? (from

Primitive live birth in ichthyosaurs

As we’ve seen before on The Dinosirs, ichthyosaurs were a very successful group of Mesozoic reptiles, highly adapted to an aquatic life.  One oft quoted adaptation viviparity, or live birth, as a fully aquatic amniote can’t get back onto land to lay eggs.  This is also seen in other groups of marine reptile, such as plesiosaurs and mosasaurs.  However, a recent paper by Motani and others has suggested that actually live birth was present in ichthyosaurs’ terrestrial ancestors before they became aquatic.  They argue this based on a fossil of a very early ichthyosaur, Chaohusaurus, which appears to have been fossilised giving birth.  While this is fairly common in ichthyosaur fossils, all previous fossils have been found giving birth to babies tail first as in modern day whales, possibly as an adaptation to prevent suffocation.  This fossil demonstrates that Chaohusaurus  gave birth head first, as in most terrestrial vertebrates.  Motani et al argue that this demonstrates that ichthyosaurs evolved from terrestrial viviparous ‘head first’ ancestors, only later switching round as an adaptation to marine life as in whales today.  This is contrary to the traditional view, but does fit with our picture of modern reptiles: many groups of lizard are viviparous.

Viviparity icthyo

Chaohusaurus.: green, red and blue below are the ribs, paddle and tail of the mother respectively. Small ichthyosaur can be seen com in out headfirst in yellow. (from Motani et al)



Dupret et al (2014) A primitive placoderms sheds light on the origin of the jawed vertebrate face, Nature

Caron et al (2014) A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies, Nature communications

Neenan et al (2014) Feeding biomechanics in Acanthostega and across the fish-tetrapod transition, Proc. Roy. Soc. B

Puttick et al (2014) High rates of evolution preceded the origin of birds, Evolution

Motani et al (2014) Terrestrial origin of viviparity in Mesozoic marine reptiles indicated by Early Triassic embryonic fossils, PLOS One

Taxon of the Week: Limusaurus


The facts


  • For your main course, it’s herbiverous.
  • To finish off with dessert, it’s got a beak.
Limusurus. Not your average ceratosaur.

Limusurus. Not your average ceratosaur.




A debate as simple as 1, 2, 3




Feduccia's (2002) argument in a nutshell.

Feduccia’s (2002) argument in a nutshell.


That’s right, a big controversy.



The small gloves are off











Taxon of the Week: Beelzebufo.



Big facts: “we’re gonna need a bigger pond”.










Big controversy





The Evanpire Strikes back





Big importance


All glory to the importance of Beelzebufo. You will obey.

All glory to the importance of Beelzebufo. You will obey.






TOTW: Pteraspis

In the spirit of Ryan’s last TOTW, this week we will be looking at a member of the group of animals that my current work focuses on: Pteraspis, a heterostracan from the Early Devonian period.

The heterostracans were a group of armoured jawless fish, or ‘ostracoderm’, which lived in both saltwater and freshwater environments from the Ordovician to the Devonian period.  They were notable for their characteristic armour, with which they evolved a wide range of forms during their existence: some encased in box-like plates, others in smaller tesserae, some with flattened bodies, others with bizarre pointy nasal structures.  I’ll probably be subjecting you to a post on heterostracan morphological diversity later on, so don’t worry too much about taking notes.


Various types of heterostracan. Pteraspis is in the bottom right. (from Wikipedia)

Heterostracans are important to palaeobiology because, despite being jawless themselves, they lie somewhere on the ‘stem’ of the phylogenetic tree of the gnathostomes, or jawed vertebrates.  In the phylogeny below, the only two living clades are the gnathostomes (jawed fish, including us), which have jaws, paired fins and a bony skeleton, and the cyclostomes (hagfish and lampreys), which have neither jaws, paired fins nor bone.  This means that fossils are the only way we have of learning about how these characters evolved.  Heterostracans themselves are particularly interesting due to their bone, one of the first occurrences of this tissue amongst vertebrates.

Gnath phylo

A cladogram of vertebrate relationships. Note how all stem gnathostomes are jawless . Extinct groups marked with a cross. (from Purnell, 2002)

Enter our hero, Pteraspis.  This 20cm long animal is pretty famous as heterostracans go, and can usually be found swimming his way through any marine Devonian diorama (there’s a particularly good one in the National Museum of Scotland, Edinburgh).  The most striking thing about Pteraspis initially is its large bony head shield.  This is characteristic of all heterostracans, although the types of plate forming it and the shape vary dependent on the species.  Characters peculiar to Pteraspis and related genera are the long rostral (ie. nose) section and the large dorsal spine.  Also worth noting are the characters it lacked.  It had no paired fins, although it’s been suggested that the two wing-like protrusions coming out of its head shield served a similar function.  It also had no jaws or teeth.


A reconstruction of Pteraspis (from Wikipedia)

As the vast majority of living vertebrates have jaws and teeth, it might be quite hard to imagine how Pteraspis would have fed. The two groups of living jawless fish- hagfish and lampreys- have highly specialised mouthparts: the former for deep sea scavenging and the other as a ‘sucker’. Heterostracan mouthparts aren’t similar to either of these however, and they also have a more generalised swimming body plan; one thing they do have though is a series of oral plates.  These were parts of the head shield (not teeth!) that lay over the oral cavity.  Many functions have been suggested: scooping sediment, grabbing onto prey and suspension feeding.  Patterns of wear seem to exclude scooping and tiny little outwards pointing denticles on the plates would have prevented big prey from entering the mouth.  As such it seems that heterostracans like Pteraspis would have suspension fed on small animals, like many groups of animal today.

Het smile

A heterostracan similar to Pteraspis giving us an oral platy grin. (from Purnell, 2002)

Pteraspis and the heterostracans have a lot to tell us about how the jawed vertebrates evolved.  They possess bone, but no jaws or paired fins, immediately telling us that these characters of the gnathostome body plan didn’t evolve together.  Although we’ve not really discussed it here, the structure of their bone itself can also teach us about the evolution of bone, and how it came to prominence as a tissue. These animals, completely different to anything living in the oceans today, also present their own mysteries, such as how they fed without jaws.  We’ve only briefly talked about heterostracans here, but fear not! There’s plenty more to talk about in the future.


What’s New(s) 31/01/14

So, only four days late putting this up.  I’ll save the things happening this week for Fridays post, but fear not! Plenty occurred in the paleontological world last week.  Some of it’s even non-Mesozoic (gasp!).


Look at those ichthyosaurs go! Diversity remains roughly constant with the Jurassic throughout their Cretaceous range. From Fischer et al.

The last hurrah of the ichthyosaurs.  This group of iconic Mesozoic marine reptiles, who recently starred in TOTW, didn’t quite make it all the way to the K/T party, and went extinct during the late Cretaceous.  Traditionally the group has been seen as going out on a bit of a whimper after a lengthy decline from the Jurassic.  New work on European ichthyosaurs by Fischer et al has shown that this picture isn’t necessarily correct, with ichthyosaurs showing a pretty stable diversity throughout their existence, at least in Europe.

Screen Shot 2014-02-04 at 10.23.53

Polypterus having a breathe. From Graham et al.

Stem tetrapods can breathe easy with the news that Polypterus, a basal ray-finned fish, breathes air through its spiracles.   These large paired openings on its had have previously been argued to have a use in air breathing, but Graham et al have for the first time demonstrated this to actually be the case.  Stem tetrapods (the lineage of fish leading up to terrestrial vertebrates, including our friend Tiktaalik) possessed spiracles which have been linked to the transition to air breathing, and this work supports this argument.


Reconstruction of the size of NHMUK R16303 (grey) in comparison to a more normally sized silesaurid. From Barrett et al.

Giant Silesaurids!  Silesaurids are a group of Triassic archosaurs thought to be somewhere near the base of the dinosaur lineage, and so are important to understanding early dinosaur evolution.  Previously silesaurids have all been fairly small animals, particularly when compared to their later dinosaurian brethren.  Barrett et al have, however, described the femur of an unprecedentedly large silesaurid from Tanzania.  This specimen, with the catchy name NHMUK R16303, shows that silesaurids gained bigger sizes than previously thought, bigger than some early dinosaurs, with implications for ideas of why and how dinosaurs were so successful.


The paper just has pictures of bits of broken femur in, so instead here’s a picture of a penguin undergoing what appears to be some kind of interview. From Wikipedia.

An ancient seabird has been described from the Palaeocene of New Zealand by Mayr and Scofield, and unlike everything else described from this locality it isn’t a penguin!  While I love penguins as much as the next man, this fleshes out the picture of the avian fauna of this area shortly after the K/T extinction.  It also continues to expand the picture of the diversity of birds in the Palaeocene, showing that the dinosaurs were still doing pretty well.  Extinct indeed.


Apologies for the decline in picture usefulness through this post, but it was a either this or a complicated schematic of the action of Hox genes which I’d have done a poor job of explaining.   From Wikipedia.

Fish fingers. For a long time, scientists have been trying to reconcile the digits of tetrapods with fishes’ fins.  These two structures that are superficially similar, but frustratingly different in layout.  While fossil data has been building up a picture of this transition, ‘evo-devo’ studies have also been providing valuable information.  One such recent study, by Woltering et al, suggests that the digits of tetrapods aren’t in fact homologous (ie. evolutionarily the same) to the fin radials in a fishes’fin.  This is based upon the expression of Hox genes (genes that dictate the layout of a developing organ) in zebrafish and mice.  When Hox genes from the fish were expressed in developing mice, they only affected development in the proximal parts (ie. arm) of the limb, suggesting fish don’t use the ‘digit-causing’ part of their genetic toolkit.  This in turn suggests the two structures are not homologous.

Taxon of the Week: Hauffiopteryx












Reconstruction of Hauffiopteryx typicus, (c) N. Tamura.

More Hauffiopteryx trivia:

  • Up to 3m long



Skull of M1399, right lateral view.














Taxon of the Week: Tiktaalik

Following all of the giant-rauisuchian based excitement of last week’s TOTW, I’ve decided to calm it down a bit by looking at an unassuming fish.  This particular unassuming fish has been in the news recently, and illustrates a transition without which there would be no Postosuchus, no mammals and (perhaps worst of all) no ‘Dinosirs’.  The fish of which I speak is, of course, the Devonian tetrapodomorph Tiktaalik roseae, but before we look at it closely, let’s have a look at the bigger evolutionary picture into which it fits.

Vertebrates that live on land are known as tetrapods, and all possess (or at least their ancestors possessed) four limbs with digits: amphibians, lizards, crocodiles, birds and mammals are all modern tetrapods. Despite their many obvious differences from what you’d typically think of as a ‘fish’, tetrapods are actually the largest group of lobe-finned fish, or sarcopterygians, named for their fins’ fleshy bases.  The only other modern groups of sarcopterygian are lungfish and the famous ‘living fossil’ coelacanth.

An African Lungfish: note fleshy-based lobe fins (from

An African Lungfish: note fleshy-based lobe fins, as compared to the rayed fins of your goldfish. (from

The most obvious difference between tetrapods and other fish is that the latter are aquatic and the former mainly terrestrial (with the exception of groups that went back into water, like whales and icthyosaurs).  At some point during the evolution of tetrapods they switched from an aquatic lifestyle to a terrestrial one, and this pretty drastic transition is of great interest to palaeontologists.   Originally pictured as being a case of fish struggling onto land and then evolving limbs, in recent(ish) years very early tetrapods from the Late Devonian (~365 Mya), such as Acanthostega and Ichthyostega, have changed this view.  These fossils have four limbs with digits, but appear to be fully aquatic, suggesting that the tetrapod body plan evolved in water first, only later proving handy (pun obviously intended) on land.

Acanth tol.web

Acanthostega having a swim with its digit-y limbs (from tol.web).

Various fish-like animals have been described that have body plans somewhere between these early aquatic tetrapods and the ancestral fishy form, and which are more closely related to tetrapods than the next closest group of sarcopterygians, the lungfish.  These animals are known as ‘tetrapodomorphs’, and show an evolutionary trajectory towards air breathing and a four-finned body plan, while still retaining fish-like characters such as gills and fin rays.  It has been suggested that this was as a result of them living in shallow rivers during the oxygen-poor Late Devonian, where being able to breathe air as well as oxygen dissolved in water would have been advantageous, as would being able to navigate shallow, relatively predator free, water.


A phylogeny of selected tetrapodomorphs and tetrapods, showing the change in body plan from ‘fish-like’ to ‘tetrapod-like’. (adapted from Daeschler et al, 2006)

Enter TiktaalikTiktaalik is something of a celebrity amongst tetrapodomorph fish. Described in 2006 from fossils found on Ellesmere Island in Nunavut, Canada, its name means ‘Burbot’ in Inuktitut.  It was subsequently popularised by one of its discoverers, Neil Shubin, in his book ‘Your Inner Fish’ (recommended), and is even the star (or possibly victim) of its own song on Youtube.  This stardom is well deserved, as Tiktaalik gives us a good deal of interesting information on the water-land transition.

A burbot reacts with indifference to the news that a tetrapodomorph has been named after it.

A burbot reacts with indifference to news of its namesake.

The original fossil material of Tiktaalik consisted of a pretty spectacularly articulated front half of the animal, possessing a number of interesting features.  The animal was pretty ‘fish-like’, but with some tetrapod-like characters, such as large shoulders bones and pectoral fins with wrist-like joints, a neck, and a robust ribcage.  These qualities, together with the shallow river environment in which it appears to have lived, led to the suggestion that it might have used its robust fore-fins to prop it up in ‘press-ups’, lifting its head (with the help of its neck) above water to breathe.  While there was no knowledge of the back half of Tiktaalik itself,  the small pelves (plural of pelvis) of other tetrapodomorph fossils like Panderichthys, led to a ‘front-wheel drive’ picture of tetrapodomorphs moving largely with the fore-fins, with  ‘four-wheel drive’ locomotion, with all four fins (or limbs), being a tetrapod innovation.

Tiktaalik wiki

Front-wheel drive Tiktaalik (from wikipedia)

Earlier this week however, the back half of Tiktaalik (or at least some of it) was described, and it transpires that this picture of exclusively ‘front wheel drive’ tetrapodomorphs is incorrect.  Tiktaaliks pelvis and parts of the hind limb were recovered, and it turns out that its hind-fins were as large as its fore-fins, with a fairly good range of movement.  While still compatible with their function as ‘props’ mentioned above, this also suggests that it would have been able to do more in terms of fin-based movement, with the possibility of underwater gaits, like the ‘walking’ seen in African lungfish.  It also changes our picture of the evolution of limbs, suggesting that tetrapodomorphs became ‘four-wheel drive’ before the evolution of tetrapods.

Tiktaalik comparison

The change in beefiness of hind-quarters/rear fins in Tiktaalik from the original description, above, to the recent paper, below (images from Daeschler at al 2006 and 2014 respectively)

While this recent information has changed our picture of Tiktaalik, it just adds to its importance as a source of information on the water land-transition.  This unassuming Devonian fish, along with various other fishy friends, helps illustrate that many of the changes that we associate with living on land, such as breathing air and having limbs, actually evolved as adaptations to aquatic life.  This transition also acts as a prime example of the mosaic nature of evolution: tetrapods didn’t evolve gradually from a fish-like form to a tetrapod-like form, but instead evolved tetrapod-like characters piecemeal while retaining ‘primitive’ ones. This mosaic theme is one that comes up time and time again in evolution, and is one that we’ll be discussing in future blog posts.

Some more Tiktaalik revelling in all their newly reconstructed glory.

Some more Tiktaalik revelling in all their newly reconstructed glory (image from

Further reading

Taxon of the Week: Postosuchus







Totally not a dinosaur. No seriously.



These coelophysoids clearly came to the wrong neighbourhood.



















bakker deino















