archosauria

2

Saichania

Mounted specimen on display at Dinosaur Kingdom, in Nakasato, Japan 

Reconstruction by Andrey Atuchin

When: Late Cretaceous (~83 to 70 million years ago)

Where: Mongolia 

What: Saichania was an armored plant eating dinosaur that roamed the deserts of Mongolia in the late Cretaceous. It was about 22 ft (~6 meters) long and heavily built. It was more fearsome looking than most armored dinosaurs as it did not just have flat armor plates on its body, but rather was covered with spikes. These dinosaurs were armored all over, there is even evidence of armored eyelids! This suit of armor would have protected Saichania from predators in the late Mesozoic mongolian desert. Fossils are typically found in deserts and badlands worldwide, but typically these areas were very different environments when the species represented by the fossils were alive. The ancient Gobi Desert was much closer to the harsh modern environment than most. Saichania was well adapted for desert life, with its stocky body and teeth designed for grinding the toughest of the desert plants. 

Saichania falls within Ankylosauridae, a group of armored dinosaurs found almost worldwide. It is one of the last and most derived of the ankylosaurids. One good way to differentiate the deserved ankylosaurids from their armored close relatives is the presence of a tail club. Saichania did not have the most massive club known, but it was still a significant feature. Ankylosaurids were one of the dinosaur groups that made it right up to the end of the Cretaceous period, vanishing with the rest of the non-avian dinosaurs. 

2

Epidexipteryx hui

…is a small species of paravian dinosaur that lived in middle or late Jurassic Asia. E.hui is known from only one well preserved partial skeleton which had four long feathers on the tail, which were composed of a central rachis and vanes. Epidexipteryx was also covered in smaller body feathers which were composed of parallel barbs. However it lacked wing feathers and could not fly, which indicates that unless E.hui evolved from flying ancestors and lost its wings, its tail feathers were advanced display feathers which might have predated flying.

Phylogeny

Animalia-Chordata-Sauropsida-Archosauria-Avemetatarsalia-Paraves-Scansoriopterygidae-Epidexipteryx-E.hui

Images: Nobu Tamura and Fucheng Zhang

Crocodilia have been with us since the age of dinosaurs, and some of them were BIG. Along with birds, they are the only surviving members of the Archosauria. (A group which included dinosaurs, crocodilia, and pterosaurs) In this artist’s conception a Deinosuchus lunges at an Albertosaurus. Illustration by Raul D. Martin, National Geographic Stock

3

Pakasuchus - the cat-like crocodile

When: Middle Cretaceous ~ 105 million years ago

Where: Tanzania, Africa

What: A Notosuchia Crocodylomorpha. Crocodiles today are all aquatic, sprawling, and fairly large (the smallest is about 5ft/1.5 meters long). However, fossil crocodiles occupied many niches and had a wide range of body types not seen in living species. A great example is Pakasuchus. This small and agile croc was completely terrestrial and only about the size of a house cat!  Its dentition was also very different from modern crocs. Living crocodiles are all homodont, all of their teeth are fairly similar cones, but Pakasuchus was heterodont like mammals. Its had not only cone like teeth, but also some teeth well suited for shearing and others for crushing and grinding. 

Pakasuchus and the rest of the notosuchians, most of which are cool enough they will be individual highlighted in future posts, are excellent examples of how the fossil record can show us lost diversity within clades that today are fairly homogenous. Crocodile line archosaurs (the clade containing crocs and dinos) were hit hard by the end Cretaceous extinction, with only modern forms surviving.  Its probable Pakasuchus or animals much like it survived to the end of the Cretaceous, even though we only have a handful of fossils from the mid-Cretaceous. Careful inspection of fossil material for distinctive Pakasuchus teeth needs to happen, and will hopefully increase it’s temporal and geographic range. 

My All Yesterday's List!

Here’s a short list of All Yesterday’s inspired behaviour/features I’d love to see depicted at some point and I’ll certainly draw myself once I get a scanner. (I’m picturing these all the dinosaurs some form of integument, by the way. Quills at least.)

  1. Iguanodon’s thumb spike as a tool for stabbing nuts/fruit and getting to edible parts.
  2. Porcupine-quilled, boar-like Heterodontosaurus bullying some nonspecific coelophysoids off a kill.
  3. Shedding Mosasaurus with some fish picking off skin flakes and eating them.
  4. Woolly Polar Triceratops bull with a broken horn fending off a similarly Woolly Tyrannosaurus
  5. Ophiacodon wrestling like Komodo Dragons.
  6. Humpbacked Spinosaurus basking on a riverside near some similarly basking crocs.
  7. Black and white with a blood-red headed Parasaurolophus male with a huge size advantage over a harem of females bullying some of his mates.
  8. Apatosaurus wading into a lake while some ornithopods ride on his back.
  9. A huge, ugly (think the T.rex from Valley of the T.rex) Eustreptospondylus tearing into some rotten icthyosaur carrion on a beach with some Rhamphorynchus trying to nab a few bites.

Anyone who reblogs should add things they’d like to see! I’m sure somebody (Probably me) will draw it eventually! I’d love to hear what people are thinking of.

Abstract

Sauria is the crown-group of Diapsida and is subdivided into Lepidosauromorpha and Archosauromorpha, comprising a high percentage of the diversity of living and fossil tetrapods. The split between lepidosauromorphs and archosauromorphs (the crocodile-lizard, or bird-lizard, divergence) is considered one of the key calibration points for molecular analyses of tetrapod phylogeny. Saurians have a very rich Mesozoic and Cenozoic fossil record, but their late Paleozoic (Permian) record is problematic. Several Permian specimens have been referred to Sauria, but the phylogenetic affinity of some of these records remains questionable. We reexamine and review all of these specimens here, providing new data on early saurian evolution including osteohistology, and present a new morphological phylogenetic dataset. We support previous studies that find that no valid Permian record for Lepidosauromorpha, and we also reject some of the previous referrals of Permian specimens to Archosauromorpha. The most informative Permian archosauromorph is Protorosaurus speneri from the middle Late Permian of Western Europe. A historically problematic specimen from the Late Permian of Tanzania is redescribed and reidentified as a new genus and species of basal archosauromorph: Aenigmastropheus parringtoni. The supposed protorosaur Eorasaurus olsonifrom the Late Permian of Russia is recovered among Archosauriformes and may be the oldest known member of the group but the phylogenetic support for this position is low. The assignment of Archosaurus rossicus from the latest Permian of Russia to the archosauromorph clade Proterosuchidae is supported. Our revision suggests a minimum fossil calibration date for the crocodile-lizard split of 254.7 Ma. The occurrences of basal archosauromorphs in the northern (30°N) and southern (55°S) parts of Pangea imply a wider paleobiogeographic distribution for the group during the Late Permian than previously appreciated. Early archosauromorph growth strategies appear to be more diverse than previously suggested based on new data on the osteohistology of Aenigmastropheus.

raptorcivilization said: Lovely, just lovely. Looks nicely intermediate between, say, Ornithosuchus and Coelophysis.

I based the reconstruction off of Euparkeria, Ornithosuchus, and Eoraptor in particular, and checked my reconstruction against the character states of the phylogenetic analysis of Sookias et al 2014.

Once again, if anyone has any critique for my reconstruction of a generalized ‘proto-archosaur’ I’d like to hear it.

Headcanon Inbound!

In Gojira’s species, there is a feature - besides the obvious - found that has no true parallels with the more standard Archosauria: External ears. These ears are small flaps on the sides of the head, not dissimilar to those of mammals. After careful observation, the purpose of having external ears when normal, ‘reptilian’ ears should suffice has been proposed. These ears, while under water, close to keep water out from the inner ear, and to prevent damage while in combat with prey or other aggressors. An almost cat-like expressiveness to the ears has been shown as a result. When angered or afraid, Gojira’s ears will flatten against its head, protecting the delicate structures inside. Though the ears cannot swivel to pinpoint noise, they have been seen to prick forward when excited or focused. In light of this discovery, it may be possible to begin predicting Gojira’s mood while making landfall, and possibly prevent an attack by refraining from using defense measures while Gojira is nonaggressive.

@legendfromthedeep

Debunking Dinosaur Myths

Do you know the answers to these dinosaur questions? Don’t rely on popular images from dinosaur movies or cartoons! They’re frequently wrong.
T. rex skull
Were all huge, prehistoric animals dinosaurs?
Did any dinosaurs swim or fly?
Were all the dinosaurs huge?
Did cavemen live alongside the dinosaurs?
Did all the dinosaurs live at the same time?
Did all the dinosaurs die out?
Why were the dinosaurs a failure?

1. Not all huge prehistoric animals were dinosaurs.

A lot of animals existed during the Mesozoic along with the dinosaurs. Some animals were closely related to the dinosaurs, like the pterosaurs (which belong to the Order Archosauria as do the dinosaurs). Birds, however, are dinosaurs! Other animals, like the Dimetrodon, which lived in the Paleozoic era before the dinosaurs existed, are more closely related to us than to the dinosaurs.

2. There were no flying dinosaurs or swimming dinosaurs.

All dinosaurs lived on the land; none of them lived in the seas or flew (until the birds)! Neither the flying pterosaurs, nor the swimming ichthyosaurs were dinosaurs, although all were closely related.
Some advanced meat-eating dinosaurs did develop feathers, and evolved into birds.


3. Not all dinosaurs were huge.

There were plenty of small and medium-sized dinosaurs. The smallest dinosaur yet discovered is Compsognathus, which was the size of a chicken!

4. People did not coexist with the dinosaurs (except for the birds).

Although the image of human cave dwellers hunting dinosaurs is well established in fiction, it is far from accurate. People didn’t evolve until about 65 million years after the dinosaurs’ extinction. Except for the birds, who are the sole surviving descendants of the dinosaurs, the dinosaurs and people are well separated in terms of geologic time.

4

amarillo, Amarillo, AMARILLO

AVE

Las aves son animales vertebrados, de sangre caliente, que caminan, saltan o se mantienen solo sobre las extremidades posteriores, mientras que las extremidades anteriores están modificadas como alas que, al igual que muchas otras características anatómicas únicas, son adaptaciones para volar, aunque no todas vuelan. Tienen el cuerpo recubierto de plumas y, las aves actuales, un pico córneo sin dientes. Para reproducirse ponen huevos, que incuban hasta su eclosión.

Su grupo taxonómico se denomina clase Aves (la palabra es latina y está en plural, en singular sería Avis) para lasistemática clásica, pero en la sistemática filogenética actual este clado no tiene rango, y es incluido a su vez sucesivamente dentro de los clados: TheropodaDinosauriaArchosauriaSauropsidaTetrapoda, etc., aunque haymás anidamientos intermedios con denominación.

Las aves se originaron a partir de dinosaurios carnívoros bípedos del Jurásico, hace 150-200 millones de años. Su posterior evolución dio lugar, tras una fuerte radiación, a las más de 10 000 especies actuales (la última lista de Clements incluye 10 157 especies vivas más 153 extintas en tiempos históricos). Las aves son los tetrápodos más diversos; sin embargo, tienen una gran homogeneidad morfológica en comparación con los mamíferos. Las relaciones de parentesco de las familias de aves no siempre pueden definirse por morfología, pero con el análisis de ADN comenzaron a esclarecerse.

Las aves habitan en todos los biomas terrestres, y también en todos los océanos. El tamaño puede ser desde 6,4 cm en el colibrí zunzuncito hasta 2,74 metros en el avestruz. Los comportamientos son diversos y notables, como en la anidación, la alimentación de las crías, las migraciones, el apareamiento y la tendencia a la asociación en grupos. La comunicación entre las aves es variable y puede implicar señales visuales, llamadas y cantos. Algunas emiten gran diversidad de sonidos, y se destacan por su inteligencia y por la capacidad de transmisión cultural de conocimientos a nuevas generaciones.

El ser humano ha tenido una intensa relación con las aves. En la economía humana las aves de corral y lascinegéticas son fuentes de alimento. Las canoras y los loros son populares como mascotas. Se usa el plumón depatos y gansos domésticos para rellenar almohadas, y antes se cazaban muchas aves para adornar sombreros con sus plumas. El guano de las aves se usa en la fertilización de suelos. Algunas aves son reverenciadas o repudiadas por motivos religiosos, supersticiones o por prejuicios erróneos. Muchas son símbolos culturales y referencia frecuente para el arte. En los últimos 500 años se han extinguido más de 150 especies como consecuencia de actividades humanas, y, actualmente, son más de 1 200 las especies de aves amenazadas que necesitan esfuerzos para su conservación.