Monday Musings: Macronaria
If you have been following my posts this month you will recall the one I did on sauropod phylogeny at the beginning. Today I am going to focus on one clade: macronaria. The name "macronaria" means "large nose" referring to the large nasal opening in their skulls.
These sauropods first appeared in the middle Jurassic about 168-161 Ma and lasted all the way until the extinction of the non-avian dinosaurs in the late Cretaceous. They have been found on every continent except Antarctica.
In review, here are the characteristics or synapomorphies we use to diagnose macronarian sauropods:
Middle and posterior neural spines have distal ends that extend out transversely.
Posterior neural spines extend at the tip forming a triangular process upwards.
The anterior chevrons have an open proximal articulation.
Robust, spatulate, broad-crowned teeth.
Crests formed by large, protruding nasal.
Forelimbs longer than hindlimbs.
Now here's a list of important or interesting macronarians:
Discovered in 1984 near Zigong, China. It's name means "delicate lizard". It is from the middle Jurassic so one of the earliest in the clade and it is known from a nearly complete skull which is almost unheard of in sauropods.
Discovered in 2005 in Queensland, Australia, the "southern giant" is the largest dinosaur found on the island continent.
Found during the infamous Bone Wars, it is the most common sauropod in the Morrison Formation. Named in 1877 by Edward Drinker Cope, it means "chambered lizard". The first specimen was recovered from Cañon City, Colorado's Garden Park Quarry. Other specimens have come from Como Bluff, Wyoming; Fruita, Colorado; Dinosaur National Monument, Black Mesa, Oklahoma; South Dakota, New Mexico, and the Snowy Mountains of Montana. Over 500 specimens are known from both juvenile and adult animals. In fact, the most complete sauropod ever found was a juvenile Camarasaurus. You've probably seen it.
There are four species recognized: C. grandis, C. lewisi, C. lentus, and C. supremus. Stratigraphic evidence suggests an evolutionary progression of the genus through the Morrison Formation. C. grandis is the oldest occurring in the lower Salt Wash Member. It coexisted briefly with C. lewisi in the upper Salt Wash and with C. lentus in the lower Brushy Basin Member before vanishing. C. lentus continued till the bottom of the upper Brushy Basin where it briefly overlapped with C. supremus. This immediate succession of species as well as similarities suggests that C. supremus evolved directly from C. lentus.
It was discovered in 1913 by a Catholic priest names Father R. Mertens and was the first dinosaur scientifically investigated in China.
Described in 2010, this titanosaur from Japan is just fun to say.
A camarasaurid found in Portugal in 1949. It comes from onw of the Morrison's sister formation, the Lourinha. It is incredibly similar to Camarasaurus with slightly longer front limbs.
A brachiosaurid from the early Cretaceous Cedar Mountain Formation. An adult and juvenile were found in 1998 in the Poison Strip Member.
A brachiosaurid known from a complete skull. Found in the Mussentuchit Member of the Cedar Mountain Formation in Dinosaur National Monument, it was very similar to Giraffatitan with narrower teeth and a smaller nose.
Found during the Bone Wars in 1900 by Elmer Riggs in Fruita, Colorado, it was the largest dinosaur ever found at the time. Despite it's popularity though, very little is actually known about this dinosaur.
Another brachiosaurid found in the Cedar Mountain Formation but in the Yellow Cat Member. Seems brachiosaurids lasted a bit in North America.
A brachiosaurid from late Jurassic Germany, it was identified as an example of insular dwarfism resulting from isolation on an island. It was only 20ft (6.2m) long!
A brachiosaurid from the other Morrison sister formation, the Tendaguru. Once thought to be a species of Brachiosaurus, most reconstructions are actually based on this genus. It is the largest sauropod known from relatively complete material. The mounted specimen in Berlin is actually a subadult at about 73.7ft (22.46m) long and 40ft (12m) tall.
A titanosaur from late Cretaceous Argentina, it is often considered the largest sauropod ever but with so little to go off that really is a bit of a leap. We need more skeletal remains.
The only titanosaur found in North America. Remains have been recovered in Texas, Utah, New Mexico, and possibly Wyoming. Despite it's name, it was actually found in New Mexico first. This one is probably kore accurately the largest sauropod as we have more material.
