Posts Tagged ‘Mesozoic’

Know Your Bones: September 2015

he_who_is_nobody
he_who_is_nobody
Wed Sep 09, 2015 6:16 am by he_who_is_nobody

Last month’s challenge led to some great guesses early on. However, the win goes to two of the later commenters. Last month, I was not looking for a specific species, but the name of the group, which makes our first winner Dragan Glas.

 

Ammonites

 

The critters are indeed ammonites (Ammonoidea). However, a minute before Dragan Glas’s guess, red also made a correct guess:

 

Perhaps otherwise – Coilopocerus nova mexicanus

 

The specimen labeled number 3 is a Coilopoceras springeri. The species is incorrect, but being able to nail down a specimen to a genus level from just a single photo is amazing. Specimen number 1 is Romanicera mexicanum and specimen number 2 is Spathites puercoensis.

 

 photo 2015-07-24 13.42.37_zpszpxyqnxe.jpg
(Taken at the New Mexico Museum of Natural History and Science)

 

Ammonites lived from the middle Devonian until the end of the Cretaceous giving them a temporal range of 400 to 66 million years ago. Ammonites are a common fossil in Paleozoic and Mesozoic marine deposits across the world. These critters would have made up a huge amount of the biodiversity of any sea during the Paleozoic and Mesozoic. Most species of ammonites have the spiral shape seen by the three species from last month’s challenge, a few others had spirals that resemble the modern nautilus, others had straight cone shaped shells, and still others had fancy shaped shells (heteromorphs). However, some of the spiral shape shelled ammonites could grow some fancy spikes to ornate their shells as well.

 

Ammonites make great index fossils, because they speciated quickly and distinctly. Thus, identifying a species (or group of species) of ammonite can actually pin down the date of a location. Ammonites can range in size from as small as 23 cm to ~2 meters in diameter. Although ammonite shells are very common, the soft bits of their body are not and very little is known about it. However, ammonites are believed to be carnivorous (like most swimming cephalopods), had a beak, and perhaps ten arms. Ammonites survived a few mass extinction events, including the end Permian extinction (the Great Dying), but finally went extinct during the K-Pg event that also took the non-avian dinosaurs.

 

Moving on to next month’s challenge:

 

 photo 2013-11-12150430_zps94e1d4e0.jpg
(Taken at the Dinosaur Museum and Natural Science Laboratory)

 

Thanks to everyone that is playing and I am hoping to read some more great guesses this month.

Know Your Bones: June 2015

he_who_is_nobody
he_who_is_nobody
Sun Jun 07, 2015 2:56 pm by he_who_is_nobody

Last month’s challenge was a stumper. For most of the month, only one person dared to give a guess. Nevertheless, it was not until days before the month ended that Isotelus came in with the correct answer.

 

The Dicynodont Placerias hesternus

 

This critter is indeed Placerias hesternus.

 

 photo 2015-06-05 09.36.01_zps3si6xnjp.jpg

(Taken at the New Mexico Museum of Natural History and Science)

 

Placerias lived during the late Triassic 221 to 210 million years ago. Placerias would have reached a length of ~3.5 meters and weighed in at nearly 1000 kilograms, making it one of the largest herbivores known about during this time. It was also one of the most common animals around during the late Triassic. Placerias had a beak and two tusks, which are common traits for dicynodonts. Both males and females had the same size tusks, thus they would have most likely used them in obtaining food and defense; not necessarily in finding mates. It is thought that Placerias would have had a life style similar to modern hippopotamuses, wallowing in semi-shallow rivers and lakes and spending little time outside of water.

 

 photo 2015-06-05 09.36.59_zps7guvthxk.jpg

(Taken at the New Mexico Museum of Natural History and Science)

 

Even though Placerias lived during the “Age of Dinosaurs” (the Mesozoic), it was not a dinosaur, it is a synapsid. Along with being a synapsid, it is also a therapsid, meaning it is very closely related to modern mammals, but falls outside of the modern mammal clade. Fossil animals, such as Placerias, are found across the world and were key evidence to help establish that at one time in earth’s past, all the continents were of one land mass (Pangaea). Dicynodonts are the second most successful synapsid clade and are only surpassed by mammals in their diversity and longevity.

 

Moving on to next month’s challenge:

 

 photo Dayatthemuseum036_zpsb8b3d5b6.jpg

(Taken at the New Mexico Museum of Natural History and Science)

 

Since last month’s was so difficult, I am hoping this one is much easier.

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