Episode 204 is all about Coelophysis, the state dinosaur of New Mexico which has been found in huge groups.

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In this episode, we discuss:

News:

Dynamoterror dynastes “powerful terror ruler,” was described from the Menefee Formation in NW New Mexico source

The dinosaur of the day: Coelophysis

Coelophysid theropod that lived in the Triassic in what is now the southwestern U.S., South Africa, and Zimbabwe

Name means “hollow form” and refers to its hollow bones that made it light

Material from similar animals have been found in some Late Triassic and Early Jurassic formations

One of the earliest known dinosaurs

Small and slender

Bipedal carnivore

Grew up to 9.8 ft (3 m) long

Weighed up to 60 lb (27 kg)

Type species is Coelophysis bauri

Two species: Coelophysis bauri and Coelophysis rhodesiensis (which was formerly Megapnosaurus)

Other species included Coelophysis longicollis and Coelophysis willistoni, now synonyms of Coelophysis bauri

Third possible species is Coelophysis kayentakatae, which was previously Megapnosaurus (but not everyone agrees)

Had a similar body shape to other theropods, with some differences

Had an S-curved neck

Coelophysis bauri had one of the earliest known wishbones in a dinosaur

Had a long, narrow head

Had forward-facing eyes, and good depth perception

Had vision about as good as eagles and hawks

Had a long snout with large fenestrae (openings), to help reduce weight

Had blade-like, recurved teeth with serrations

Teeth were good for slicing

Probably ate small, lizard-like animals

May have been an opportunistic carnivore (predator and scavenger)

Fast and agile

Had long legs

Had a long, slender neck and tail

Had a semi-rigid tail (didn’t move up and down)

Had four digits on its hand, but only three were functional

Had narrow hips

Had forelimbs it could use for grasping

In 2002, Carpenter found that Coelophysis had flexible forelimbs, though they were weak. That, and small teeth, means Coelophysis probably preyed on animals much smaller than itself. Also found Coelophysis to be a “combination grasper-clutcher”

Had narrow feet

Had three toes

Two forms: gracile and robust

Gracile form has a longer skull and neck, shorter forelimbs

Robust form has a shorter skull and neck and longer forelimbs

May be due to sexual dimorphism (gracile may have been female, easier for egg laying)

About 50% of the population found was gracile, and 50% robust, further supporting sexual dimorphism

However, later research found that both species of Coelophysis had variable growth, and the gracile and robust forms may be just individual variation

Rinehart and others found in 2009 that female Coelophysis would have laid 24-26 eggs in each clutch, and found some evidence of some parental care during the first year of their hatchling’s life

Grew rapidly, especially during the first year they lived

Probably reached full size by the time it was eight years old

Named in 1887 by Edward Drinker Cope, described by Cope in 1889

David Baldwin, an amateur fossil collector who worked for Cope found the first bones in 1881 in the Chinle Formation in New Mexico

Coelophysis bauri was originally named Coelurus bauri

Cope referred to these specimens as Coelurus bauri and Coelurus longicollis in 1887, then reassigned them to Tanystrophaeus later that year

In 1889, Cope reassigned/renamed those bones to Coelophysis bauri

Species named for Georg Baur, a comparative anatomist who had similar ideas to Cope

Synonyms: Longosaurus, Rioarribasaurus, Megapnosaurus

The first bones were not well preserved

In 1947, George Whitaker, assistant to Edwin Colbert (from AMNH), found a Coelophysis bonebed of hundreds (maybe over 1,000) specimens in New Mexico at the Ghost Ranch, near where the first fossils were found

Colbert assigned the fossils to Coelophysis. So many specimens were found, and one became the new diagnostic specimen for Coelophysis

In the 1980s there were debates that the first Coelophysis specimens were not diagnostic by themselves, and that other specimens could not be applied to Coelophysis bauri and said in 1991 that the Ghost Ranch quarry specimens should be Rioarribasaurus. However, the fossils from Ghost Ranch were called Coelophysis in most scientific papers, which would make switching them to Rioarribasaurus confusing, so there was a petition to change the type specimen of Coelophysis to one of the Ghost Ranch specimens

The ICZN voted to make one of the Ghost Ranch specimens the new type specimen and declared Rioarribasaurus a nomen rejectum (rejected name), and Coelophysis became a nomen conservandum (conserved name)

May have hunted in packs (based on Ghost Ranch bonebed)

No direct evidence that Coelophysis hunted in packs, just that they were buried together

May have been because they all drank at a water hole or went to eat fish, and then died by a catastrophic flash flood or a drought

30 specimens of Coelopysis rhodesiensis were found together in Zimbabwe (no direct evidence of pack hunting), may also have died from a flash flood

In 1969 Mike Raath described Syntarsus rhodesiensis

Syntarsus means “fused ankle”

Michael Ivie and others, who studied beetles, found that Syntarsus was already the name of a beetle, that was named in 1869. Because Ivie and his team figured this out, they were able to rename the dinosaur. They named it Megapnosaurus (means “big dead lizard”) though Raath did not like it. Ivie and his team did not contact Raath beforehand to tell him either

Raath argued in 2004 that Megapnosaurus (Syntarsus) was a junior synonym of Coelophysis. Others agreed in other papers throughout the years

In 2005 Yates found that Coelophysis and Megpnosaurus were nearly identical and suggested they synonymize them

In 2004 Tykoski and Rowe found it to be synonymous with Coelophysis (confirmed in 2007 by Ezcurra and Novas)

In 2000, Downs found that another dinosaur, Camposaurus arizonensis, was a junior synonym of Coelophysis bauri, though in 2011 Martin Ezcurra and Stephen Brusatte found Camposaurus was distinct enough to be its own genus, though it was closely related to Ceolophysis rhodesensis

Professor Mignon Talbot found a specimen in 1911 that she named Podokesaurus holyokensis that for a while was considered to be related to Coelophysis but now some people think is a synonym

Some scientists think Coelophysis bauri is the same as Coelophysis rhodesiensis (used to be Syntarsus, also known as Megapnosaurus). But in 2000 Downs and in 2004 Tykoski and Rowe, and also Bristowe and Raath found that Coelophysis bauri is different from Coelophysis rhodesiensis

Thought to be cannablistic, based on juvenile specimens being found in the guts of some of the specimens from Ghost Ranch

In 2002, Robert Gay found this was misinterpreted, and instead the “juvenile coelophysids” were small reptiles. Nesbitt and others supported this in 2006

In 2009, Rinehart and others re-examined a specimen and found teeth and jaw bone fragments in and around the mouth that were “morphologically identical” to juvenile Coelophysis

In 2010, Gay found that the volume of bones was 17 times greater than the maximum estimated volume of a Coelophysis stomach, and also found an absence of tooth marks, and that the juvenile bones were deposited stratigraphically below the animal that ate them. He found that the position they were found in were a “coincidental superposition of different sized individuals”

Coelophysis that lived in what is now New Mexico lived in a warm, monsoon-like climate

Coelophysis rhodesiensis lived among desert dunes

Coelophysis was the second dinosaur in space (after Maiasaura). A Carnegie Museum Coelophysis skull was on the Space Shuttle Endeavour mission STS-89 in January 1998, and was also taken to the space station Mir before going back to Earth

Official state dinosaur of New Mexico, and is the logo of the New Mexico Museum of Natural History

Coelophysis bauri became New Mexico’s state fossil in 1981

Can see Coelophysis in the first episode of Walking with Dinosaurs

Fun Fact:

Dinosaurs may have had a nictitating membrane (like modern bids do) and so did the Indoraptor puppet in Jurassic World: Fallen Kingdom

Sponsors:

This episode is brought to you in part by TRX Dinosaurs, which makes beautiful and realistic dinosaur sculptures, puppets, and animatronics. You can see some amazing examples and works in progress on Instagram @trxdinosaurs