Introduction
Nedcolbertia (named in honor of the American paleontologist Dr. Edward “Ned” Colbert, 1905-2001) was a mysterious and intriguing creature which inhabited western North America during the early Cretaceous Period about 140-130 million years ago. When it was officially named and described in 1998, it was identified as a coelurosaur – the same family of meat-eating dinosaurs that creatures like Coelurus and Ornitholestes belong to. Then in 2017, it was re-classified as a primitive ornithomimosaur – the so-called “ostrich mimic” dinosaurs, which include creatures like Ornithomimus, Struthiomimus, and Gallimimus from the 1993 movie Jurassic Park. However, with new discoveries made in South America, Europe, and Australia, I am proposing a new hypothesis: Is it possible that Nedcolbertia is actually an elaphrosaur?

The Elaphrosaurs: The “Ostrich Mimic” Mimics of the Mesozoic
If you don’t know what an “elaphrosaur” is, don’t feel bad, since they’re not the most well-known dinosaurs out there. The “elaphrosaurs” are a sub-family of the theropod family Noasauridae (who are close relatives of the abelisaurs like Abelisaurus and Carnotaurus), which in turn is within the greater theropod clade Ceratosauria (1). The elaphrosaurs appeared during the middle of the Jurassic Period and they continued on into the middle of the Cretaceous Period. Although they are theropods, which are mostly carnivores, the elaphrosaurs evolved to be plant-eaters just like the therizinosaurs would do during the Cretaceous (2). The elaphrosaurs bear a strong physical resemblance to the ornithomimosaurs despite not being closely related to them, and to some oviraptorosaurs which would come later, as well as to the crocodile-like shuvosaurids which had appeared earlier during the Triassic Period.

Only a handful of elaphrosaur species are currently known, which include:

1. Limusaurus inextricabilis, from the middle-to-late Jurassic of China, about 160-155 MYA. Measured 6 feet long.
2. Elaphrosaurus bambergi, from the late Jurassic of Tanzania, about 150 MYA. Size unknown due to partial remains, but it’s estimated at 15-20 feet long, making it the largest elaphrosaur known.
3. An unidentified elaphrosaur from the middle Cretaceous of southeastern Australia, about 110 MYA. Known from a single neck vertebra. Total length unknown.
4. Huinculsaurus montesi, from the middle Cretaceous of Argentina, about 95 MYA. Size unknown due to partial remains, but it’s estimated at 10 feet long.

There might be more elaphrosaur species than the four listed above. Skeletons which have been found in southwestern France are almost certainly elaphrosaurine, although this animal has not been officially classified yet. Furthermore, isolated remains which have been found in the Morrison Formation of western North America (3) and in the Wealden Formation of southern England (4) have been tentatively identified as being elaphrosaurine, although the remains are too fragmentary to make their identification certain.

The elaphrosaurs as a whole, and the eponymous Elaphrosaurus in particular, have had a confusing history of identification and re-identification. When its remains were found in Africa in 1910, and officially named by Werner Janensch a decade later in 1920, it was originally classified as a coelurosaur due to the slenderness of its bones. However, in all fairness, at that time “coelurosaur” was a general term for any small lightly-built theropod, in contrast to the heavy massive “carnosaurs”, and therefore wasn’t very diagnostic (5). Werner Janensch observed that some of the bones seemed similar to that of ornithomimosaurs (6), and the famous European paleontologist Franz Nopcsa also suggested that Elaphrosaurus might be an early ornithomimosaur. However, this idea was not accepted until the 1970s when Elaphrosaurus was re-classified as a primitive ornithomimosaur (7). During the late 1980s, Gregory Paul proposed that it was actually a late-surviving Coelophysis-like theropod (8), although this claim was not accepted by most paleontologists. Finally during the 2000s, Elaphrosaurus was re-classified again as a ceratosaurian, specifically within the ceratosaur family Noasauridae (9).

The original illustration of an Elaphrosaurus bambergi skeleton made by Werner Janensch in 1920 which incorrectly depicts it as a coelurosaur similar to Ornitholestes. Since no skull material was found, the outline of the head was conjecture. From Glut, Donald F. Dinosaurs: The Encyclopedia. Supplement 2. Jefferson: McFarland & Company, Inc., 2000. Page 325.

Part of the reason why Elaphrosaurus’ identity was so difficult to pin down was because elements of its skeleton look very similar to the bones of other animals. The elaphrosaurs have often been mistakenly identified as either coelurosaurs or ornithomimosaurs. This is because the bones of elaphrosaurs look strikingly similar to the bones belonging to those two other groups, with only a few minor differences, and this can make them difficult to tell apart. For example, the shape of its humerus (upper arm bone) looks almost exactly like the humeri of ornithomimosaurs, and this was presented as diagnostic evidence for re-classifying Elaphrosaurus as an ornithomimosaur (10). This is a prime example of what is called “convergent evolution”, where different groups of organisms evolve to have the same appearance. However, just because they look similar to each other, that doesn’t necessarily mean that they’re directly related to each other. This is what is known as “synapomorphy”, when the body parts of different animals look very similar or even identical to each other, even though they aren’t closely related. What is needed is what’s called “autopomorphy”: an anatomical feature which is only seen in one particular species and which no other animal has. Autopomorphies are used by paleontologists to diagnose a particular animal as being its own separate species.

Leg of Elaphrosaurus bambergi, showing the short femur in relation to the tibia and fibula, and the elongated metatarsal bones – all of which are indicative of a fast runner. Janensch, Werner (1920). “Über Elaphrosaurus Bambergi und die Megalosaurier aus den Tendaguru–Schichten Deutsch–Ostafrikas”. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin (1920). Page 228.

Elaphrosaurs didn’t just live in Africa, but throughout the prehistoric southern continent of “Gondwana”, which in the Jurassic Period included South America, Africa, India, Australia, and Antarctica. In 1991, a series of five vertebrae were discovered in the Huincul Formation of west-central Argentina within rocks dated to the middle of the Cretaceous Period, about 95 MYA. Yet it wasn’t until 2020 that these bones were carefully examined, and it was concluded that they belonged to an elaphrosaur, which was given the name Huinculsaurus. Its discovery proved two things: first, that elaphrosaurs lived in South America, and second, that they were not restricted to the Jurassic Period but continued on into the Cretaceous.

The same year that a scientific paper was published stating that elaphrosaurs lived in South America, two papers were published stating that they lived Australia as well. In January of 2020, evidence was presented that ceratosaurian theropods lived within the Land Down Under. A cervical vertebra had been discovered in New South Wales within rocks of the Cenomanian Stage of the Cretaceous Period, about 100-95 MYA. Additionally, a left astragalocalcaneum (which forms part of the ankle) which had been discovered in Victoria within rocks dated from the upper Barremian to the lower Albian Stages of the Cretaceous, about 125-110 MYA. Both of these fossils were ascribed to a member of the ceratosaurian family Noasauridae – the same group that the elaphrosaurs belonged to. The authors even noted that the neck vertebra found in New South Wales looked very similar to the neck vertebrae of Elaphrosaurus, but they did not outright state that the bone belonged to an elaphrosaur (11).

Then just a few months later in May, another paper was published stating that another cervical vertebra measuring just 5 cm long was found in 2015 in Victoria within rocks dating to the middle Cretaceous Period about 110 MYA. Originally identified as a pterosaur neck bone, it was re-examined, and was re-identified as belonging to an elaphrosaur (12). The findings were written up in a scientific article published in 2020 (13).

The discovery of one or two elaphrosaur neck vertebrae within Australia in rocks dated to the middle Cretaceous raises an interesting question pertaining to other Australian dinosaurs which were found and described earlier. During the early 1990s, a dinosaur found in Australia named Timimus was identified as an ornithomimosaur. However, with the discovery of an elaphrosaur in Australia, this now throws this identification into doubt. Considering that elaphrosaurs are often confused with ornithomimosaurs, this leads one to ask if Timimus is really an ornithomimosaur, or is it actually an elaphrosaur? But this is perhaps a research topic for another day.

Elaphrosaurs didn’t just inhabit the southern parts of the globe, but the north as well. During the early 2000s, a team of Chinese and American paleontologists were prospecting for fossils within the rocks of the Shishugou Formation, located in the Junggar Basin of northwestern China, within the region known as Uyghurstan. Within these rock layers dated to the middle and late Jurassic Period, several fossil-rich bone beds were discovered. Among the bones which were found were the skeletal remains of a small theropod dinosaur measuring about 6 feet long. These were identified as belonging to a ceratosaurian, and in particular, to an elaphrosaur, which had previously only been known from Africa. In 2009, it was named Limusaurus. Unlike the fragmentary remains which had been found in Africa during the early 20th Century, and also unlike the partial remains uncovered in South America and Australia, the fossils found in Uyghurstan consisted of a sizeable percentage of the animal’s skeleton, including the skull. Furthermore, not only did we have adults, but we also had juveniles as well, which showed how the animal’s skeleton changed as it grew. This discovery gave us the clearest picture of what an elaphrosaur would have looked like, and it also proved that the elaphrosaurs were not restricted solely to Gondwana, but potentially had a more world-wide range (14).

Skeleton of Limusaurus inextricabilis, an elaphrosaur from China. Modified from Wang, Shuo; Stiegler, Joseph; Amiot, Romain; Wang, Xu; Du, Guo-hao; Clark, James M.; Xu, Xing (2017). “Extreme Ontogenetic Changes in a Ceratosaurian Theropod”. Current Biology, volume 27, issue 1 (January 9, 2017). Pages 144-148.

Further evidence that the elaphrosaurs were more wide-ranging than previously thought was uncovered in western Europe. In 2008 near the village of Angeac-Charente within southwestern France, workers were digging in a gravel quarry when they discovered what looked like dinosaur bones sticking out of the ground. A team of French paleontologists were brought in to excavate the site further, and to their great astonishment, they found the area to be virtually carpeted with bones. The rocks that the fossils were found in were dated to the Berriasian Stage and early Valanginian Stage of the early Cretaceous Period, approximately 144-135 million years ago. Over the course of several dig seasons, fossils of numerous animals were discovered there including fish, turtles, crocodiles, mammals, and several kinds of dinosaurs. However, the one type of animal of which there was more fossil material than anything else was a slim medium-sized theropod dinosaur measuring 18 to 20 feet long. Most of the remains were found disarticulated, similar to that seen in Dinosaur National Monument and at the Dalton Wells Quarry, which indicate that these bones were carried and deposited by a flash flood. In a 2012 report, it was stated that at least eight or nine individuals of this species were recovered from this bonebed, but by the year 2022, that number has since grown to seventy, and it may continue to grow further still. In terms of percentages, fossil material from this creature amounts to 50% of all of the fossils recovered from this site. Some of the specimens were described in Allain et al (2014), but most of the specimens are as-yet undescribed (15).

The paleontologists who uncovered the bones originally identified this creature as a primitive ornithomimosaur similar in some respects to Pelicanimimus, a primitive ornithomimosaur found in Spain. According to Allain et al (2014), this dinosaur was identified as an ornithomimosaur partly based upon its overall appearance and also due to the following four anatomical features (16):

1. Edentulous (meaning “lacking teeth”) and down-turned dentary.
2. Flexed cervical prezygapophyses.
3. A sigmoid ischial shaft.
4. Toe claws with flat undersides.

However, as more bones and skeletons were uncovered, and as paleontologists got a clearer picture of what the entire animal would have looked like, some began having second thoughts about this identification. The vertebra which was recovered in southeastern Australia looked almost identical to the vertebrae of Elaphrosaurus, which in turn looked similar to the vertebrae of the “ornithomimosaur” skeletons uncovered in southwestern France. This “ornithomimosaur” from the Angeac-Charente Bonebed bore a striking resemblance to the skeletons of Elaphrosaurus of Africa and Limusaurus of China, notably its short stubby arms, its tiny fingers, and the shape of its shoulder girdle, and therefore it ought to be re-classified as an elaphrosaur (to see an illustration of this skeleton by the French artist Mazan, click here). If this identification is correct, then it would be the first confirmed example of an elaphrosaur found in Europe, and the second one known from the Northern Hemisphere (17).

The skull of the Angeac “ornithomimosaur”, which actually bears a much stronger similarity to an elaphrosaur. From the travelling exhibit Dinosaures, les Géants du Vignoble, on display at the Natural History Museum of La Rochelle (Muséum d’Histoire Naturelle de La Rochelle) from April 14, 2018 to September 1, 2019. This exhibition was most recently on exhibit at the Jurassica Museum (Porrentruy) from April 2, 2021 to February 27, 2022. https://sgnamh.fr/spip.php?article283.

Or is it? Has a European elaphrosaur been found before? Possibly. The early Cretaceous theropod Valdoraptor, whose fossils have been found in southern England, has also been identified as a primitive ornithomimosaur. However, the British paleontologist Darren Naish pointed out that the bones ascribed to Valdoraptor look very similar to the skeletons found in southwestern France, and that they might belong to the same animal (18). If this is correct, then elaphrosaurs would be even more widespread and this has strong implications for just how far of a geographic range these animals had. If they lived in South America, Africa, Australia, Asia, and Europe, then could they have also lived in North America as well?

Basal Ornithomimosaurs in North America
During the 1970s, thanks to fossil finds in North America which are traditionally associated with the early Cretaceous of Europe, it was proposed that western Europe was connected to the northern part of North America during the late Jurassic and early Cretaceous Periods via a trans-Atlantic land bridge. Numerous scientific studies carried out during the 1990s, 2000s, and 2010s re-affirmed this (Plafker and Berg, 1994; Kirkland et al, 2015; Cifelli et al, 1997; Cifelli and Muzion, 1997; Kirkland et al, 1997; Kirkland et al, 1998b; Kirkland et al, 1999; Kirkland and Madsen, 2007; Martill and Naish, 2010a; Kirkland et al, 2013a; Kirkland et al, 2015; Brikiatis, 2016; Kirkland et al, 2016). In particular, Leonidas Brikiatis’ 2016 report was the most thorough. In it, he states that it wasn’t until 129 MYA, during the time of the Cedar Mountain Formation’s Poison Strip Member, that the Atlantic Ocean expanded to such an extent that North America was at last permanently severed from Europe. For a period afterwards measuring approximately twenty-five or so million years, North America was completely isolated from the rest of the Mesozoic world. It wouldn’t be until the late Albian Stage about 105-100 MYA that a second land bridge appeared, this time spanning the northern Pacific, connecting Alaska with Russia (19).

Because the Atlantic Ocean was still in the process of growing during the late Jurassic and early Cretaceous, and had not yet completely split North America from Europe, it was possible for animal species to travel between the two continents via a trans-Atlantic land bridge. The scientific term for this is “faunal interchange”. Evidence for this consists of animals which are traditionally associated with Europe such as megalosaur theropods, turiasaurian sauropods, and iguanodont ornithopods also being found within North America. If faunal interchange could occur one way, then it’s certainly plausible that it could go the other way as well. Indeed, fossils of dromaeosaurid theropods, which are known to have inhabited North America during the early Cretaceous Period, have also been found within contemporaneous early Cretaceous rocks of England (20), France (21), and Denmark (22). Since elaphrosaurid theropods have been found within France (and possibly England) in rocks dating to the early Cretaceous Period approximately 140 MYA, then it’s possible that these creatures could have eventually made their way into North America as well. However, while it is hypothetically possible that they could have done so, is there any hard evidence to actually prove it?

In 1990, paleontologists were digging approximately half a mile northeast of a place called “Gaston Quarry” in eastern Utah within rocks of the Yellow Cat Member of the Cedar Mountain Formation. There, they uncovered three partial skeletons of a small theropod dinosaur: one juvenile and two sub-adults (collections ID codes: CEUM 5071, CEUM 5072, and CEUM 5073, respectively). These are currently housed within the Prehistoric Museum of Utah State University-Eastern, formerly known as the College of Eastern Utah Museum, but the old classification codes are still used (23).

Right foot of a juvenile specimen of an unidentified maniraptoran theropod, discovered at Gaston Quarry in 1990. This was later given the name Nedcolbertia. From Kirkland, James I.; Britt, Brooks; Burge, Donald L.; Carpenter, Kenneth; Cifelli, Richard; DeCourten, Frank; Eaton, Jeffery; Hasiotis, Stephen; Lawton, Tim (1997). “Lower to Middle Cretaceous Dinosaur Faunas of the Central Colorado Plateau: A Key to Understanding 35 Million Years of Tectonics, Evolution, and Biogeography”. Brigham Young University Geology Studies, volume 42, issue 2. Page 98.

Kirkland, James I.; Britt, Brooks B.; Whittle, Christopher H.; Madsen, Scott K.; Burge, Donald L. (1998). “A small coelurosaurian theropod from the Yellow Cat Member of the Cedar Mountain Formation (Lower Cretaceous, Barremian) of eastern Utah”. New Mexico Museum of Natural History and Science Bulletin, volume 14 (1998). Page 246.

News of its discovery was publicly announced in January of 1995, although the announcement itself consisted of just a short blurb stating that the bones had been found (24). In 1997, James Kirkland and his associates identified the animal (which still had not yet been named) as a coelurosaur similar to Ornitholestes, but stated that it was likely a new genus, as Ornitholestes was known exclusively from the Morrison Formation of the late Jurassic Period (25). It wasn’t until 1998 that the creature was officially given a name – Nedcolbertia justinhofmanni. Once again, the creature was identified as a coelurosaur similar to Ornitholestes, although the authors of the paper cautioned that its identification as a coelurosaur could not be stated with certainty. It’s classification within Coelurosauria was largely based upon the shape of its ankle, specifically “the expansive ascending process of the astragalus” (26).

In addition to the three partial skeletons found half a mile away from Gaston Quarry, fossils found at Dalton Wells have also been ascribed to Nedcolbertia (27). All of these specimens are dated to the upper part of the Yellow Cat Member of the Cedar Mountain Formation, dating approximately 135-132 MYA. There has been a report that a fourth Nedcolbertia skeleton was discovered in the same area where the other three were found, excavated by a team from Brigham Young University. However, this skeleton has not been described yet (28).

Within the 1998 research paper which named Nedcolbertia, Kirkland and his colleagues referenced a similar animal which had been found in the Arundel Formation of mid-Cretaceous Maryland during the early 1900s (Charles W. Gilmore, 1920 and 1921), as well as another animal which had been found in the Trinity Group of southwestern Arkansas (J. H. Quinn, 1973) (29). The Arkansas theropod was officially named Arkansaurus fridayi in 2018, and was identified as an ornithomimosaur (30). As for the ornithomimosaur remains found within Maryland, Chase Brownstein has proposed that they likely belong to two different species, although neither of them had yet been given names (31).

Foot of Arkansaurus (collections ID code: AU 74-16). A) Top view of the ends of the metatarsal bones. B) The entire foot. These bones are very similar to Nedcolbertia. Kirkland, James I.; Britt, Brooks B.; Whittle, Christopher H.; Madsen, Scott K.; Burge, Donald L. (1998). “A small coelurosaurian theropod from the Yellow Cat Member of the Cedar Mountain Formation (Lower Cretaceous, Barremian) of eastern Utah”. New Mexico Museum of Natural History and Science Bulletin, volume 14 (1998). Page 247.

While the 1998 paper provisionally identified Nedcolbertia as a coelurosaur, it was pointed out in a 2017 paper by Chase Brownstein that several parts of this creature’s anatomy bore strong similarity to that seen in ornithomimosaurs, largely pertaining to leg and foot morphology. Because of these features, Brownstein came to the conclusion that Nedcolbertia was not a coelurosaur, as had been proposed in Kirkland et al (1998), but was in fact a basal ornithomimosaur similar to Harpymimus or Nqwebasaurus (32).

However, is it possible that this, too, is a mis-identification? After all, Elaphrosaurus itself was originally identified as a coelurosaur, only to be re-classified later as a basal ornithomimosaur, until it was at last re-classified once again as a ceratosaurian. Is it possible that Nedcolbertia was also an elaphrosaur as well? If so, then it would be the first confirmed example of one found within North America. But is it? Let’s carefully examine the evidence.

Was Nedcolbertia an Elaphrosaur?
It must be said that the anatomy of Nedcolbertia shares similarities with the anatomy of elaphrosaurs. After all, Nedcolbertia was originally classified as a coelurosaur, and then re-classified as an ornithomimosaur…just like with Elaphrosaurus. For example, the vertebrae of Elaphrosaurus are very similar in appearance to the vertebrae of ornithomimosaurs, being of similar shape and proportions (33). However, just exactly how similar are Elaphrosaurus and Nedcolbertia to each other? Maddeningly, no skull material has been found ascribed to Nedcolbertia which would clinch the creature’s identity as to whether it is an elaphrosaur or an ornithomimosaur. Mostly, our compare-and-contrast examination pertains to vertebrae and leg bones.

According to Rauhut and Carrano (2016), Elaphrosaurus possesses the following anatomical features (34):

1. The cervical vertebrae were elongate in general shape, with deep depressions running along their sides. The neck vertebrae were flat to slightly concave on their undersides, and they did not possess a keel or ridge running up the middle. The prezygapophyses (the knobs on the front of the vertebrae) and the postzygapophyses (the knobs on the rear of the vertebrae) of the cervical vertebrae were narrow, over 1.5 times longer than they were wide. The posterior ends of the neck vertebrae possessed pronounced ventro-lateral laminae. The cervical vertebrae did not possess epipophyses.
2. There were no pleurocoels or pleurocoelous fossae present within the vertebral centra of both the posterior cervical and anterior dorsal vertebrae.
3. The scapula (shoulder blade) possessed a very broad shaft, being 20% or more of the anteroposterior length of the element. There was a deep vertical groove over the glenoid on the proximal end of the scapula.
4. Straight humerus (upper arm bone), with rounded proximal head and reduced deltopectoral crest, which turns medially distally.
5. Shortened metacarpal bones. The distal end of the second metacarpal is offset ventrally from the metacarpal’s shaft by a distinct step.
6. Six sacral vertebrae.
7. The ilium (the bone that forms the top of the hip) possesses a short shelf which flares out sideways.
8. The pubis (the bone that forms the front of the hip) is missing a proximal plate and obturator foramen.
9. The ischium (the bone that forms the rear of the hip) possessed a large backwards-pointing flange on the ischium’s posterior side. The ischium also lacks a distal incision between obturator flange and shaft, but it does have a well-developed distal boot.
10. Femur with anteromedially directed head and expanded (wing-like) lesser trochanter.
11. Tibia with anteriorly flattened distal end that is broad and triangular in outline.
12. Fibula with large depression on the medial side of the proximal end; proximal shaft of metatarsal II less than 50% the width of metatarsal IV.
13. Proximal end of metatarsal IV almost 2.5 times deeper anteroposteriorly than wide transversely. If the ascending process of the astragalus is correctly identified, its extremely small size, extending for only ~3% of the length of the tibia, represents another apomorphy.
14. Mid-caudal vertebrae with low, rectangular neural spines.
15. Distal caudal vertebrae with centra that are considerably wider than high and with considerably broadened prezygapophyseal bases.

According to Kirkland et al (1998), anatomical features of Nedcolbertia include (35):

1. The vertebrae only possessed rudimentary pneumaticity, unlike the vertebrae of ornithomimosaurs.
2. The proximal end of one humerus is known from one specimen of Nedcolbertia (CEUM 5073). Based upon its size and shape, it has “a well-developed, central articular head that only moderately thickens the proximal end of the humerus” (36). The distal end of another humerus is known from the holotype, a juvenile (CEUM 5071), which possesses a slender shaft which widens sideways.
3. Its hands possessed long slender phalanges (finger bones), with a large claw on the end of its thumb with a large robust flexor tubercle, while its second finger had a smaller and more-slender claw with a less-developed flexor tubercle; only the proximal half of both claws were preserved. Having differently-proportions claws on each of the fingers is a feature not seen in ornithomimosaurs, whose hand claws are more-or-less identical to each other.
4. The structure of the femur was not like the femurs of any maniraptoran theropods, including ornithomimosaurs, oviraptorosaurs, therizinosaurs, and deinonychosaurians. The femur was “medially bowed”, meaning that it was slightly curved towards the middle of the body.
5. The “anterior trochanter” was shorter than the “greater trochanter”, unlike that seen in Maniraptoriformes.
6. The legs as a whole were long and slender, with a short femur, a long tibia and fibula, and long metatarsals.
7. The tail vertebrae are amphicoelous, meaning that the front and rear faces of the vertebrae centra are concave, and were spindle-shaped when viewed from below.

According to Chase Brownstein (2017), anatomical features of Nedcolbertia include (37):

1. An elongated femur with the femoral head directed straight medially and not separated from the greater trochanter by a sulcus.
2. A large cnemial crest on the tibia which curves laterally toward the crest’s tip.
3. A tall ascending process on the astragalus.
4. A complex space on the lateral side of the astragalus into which the calcaneum fits.
5. A sulcus separating the astragalar condyles.
6. There is no sulcus present for separating the femoral head from the greater trochanter.
7. The proximal end of metatarsal III is restricted mediolaterally in a very similar fashion to Harpymimus, and in proximal view the metatarsals are similar in shape to those of Kinnareeemimus and Nqwebasaurus.
8. The phalanges from pedal digit IV are anteroposteriorly shortened.
9. The ventral surfaces of the pedal ungual are flattened in lateral view and triangular in proximal view.
10. The pedal unguals are elongated and possess deep lateral grooves for the claw sheath.
11. The ventrolateral and ventromedial edges of the pedal unguals are developed into keels.
12. The ventral surface of its pedal unguals have a flexor fossa on the proximal end.
13. Elongated caudal vertebra.

Several features seen in Nedcolbertia are seen in ornithomimosaurs, but they are also seen in elaphrosaurs. These include toe claws with flat bottoms, which are often regarded as being a diagnostic trait for ornithomimosaurs. However, while the feet may be similar to each other, the hands are a different story entirely. Kirkland et al (1998) stated that Nedcolbertia possessed long slender finger bones, which is quite a contrast to the short stubby phalanges that elaphrosaurs are known to have. This alone seems pretty conclusive that Nedcolbertia isn’t an elaphrosaur. Furthermore, the hands possessed large claws similar to that seen in numerous types of theropod dinosaurs. Again, this is in contradiction to the morphology of elaphrosaur hands, which had tiny claws (38).

Hand claws from Nedcolbertia, specimen CEUM 5072 (sub-adult #1). O = claw from second finger; P = thumb claw. The slight curvature of the dorsal surface of both claws indicates that the hand claws were very straight and would have been quite long. Scale bar = 2 cm. Kirkland, James I.; Britt, Brooks B.; Whittle, Christopher H.; Madsen, Scott K.; Burge, Donald L. (1998). “A small coelurosaurian theropod from the Yellow Cat Member of the Cedar Mountain Formation (Lower Cretaceous, Barremian) of eastern Utah”. New Mexico Museum of Natural History and Science Bulletin, volume 14 (1998). Page 246.

A thumb claw from a large ornithomimid theropod dinosaur found in Alberta, Canada (ROM 41844). Longrich, Nick (2008). “A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: Implications for the study of dissociated dinosaur remains”. Palaeontology, volume 5, issue 4 (July 15, 2008). Pages 983-997.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1475-4983.2008.00791.x.

Three ornithomimosaur hand claws found in Alberta, Canada. A = ROM 41844. B = TMP 93.109.43. C = 2005.049.0021. While these three specimens have been assigned to three separate species, it’s possible that they might in fact belong to the same species and represent the first, second, and third unguals of one hand. The size and physical proportions are very similar to the hand claws of Nedcolbertia. Longrich, Nick (2008). “A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: Implications for the study of dissociated dinosaur remains”. Palaeontology, volume 5, issue 4 (July 15, 2008). Pages 983-997.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1475-4983.2008.00791.x.

Left arm of Hexing qingyi, a primitive ornithomimosaur found in China, showing the proportions of the upper arm, lower arm, and hand. Jin, Liyong; Chen, Jun; Godefroit, Pascal (2012). “A new basal ornithomimosaur (Dinosauria: Theropoda) from the Early Cretaceous Yixian formation, Northeast China”. In Godefroit, P., ed. Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems. Bloomington: Indiana University Press, 2012. Page 478.

The arrangement of the metatarsal bones within Elaphrosaurus is also different compared to those of Nedcolbertia. In Elaphrosaurus, the rear side of the middle metatarsal bone (metatarsal III) flared outwards laterally on both sides, forming what looks like a capital letter T in cross-section. The arms of this T-shape hold the other metacarpals in place, with metacarpal II and metacarpal IV neatly slotting into the sides of metacarpal III. By contract the metatarsal bones of Nedcolbertia do not exhibit this arrangement. Its third metatarsal bone is perfectly straight on its medial side, and is S-shaped on its distal side. These contours are mirrored within the adjoining metatarsals, with metatarsal II having a straight side where it abuts against metatarsal III, and with metatarsal IV having an S-shaped curvature so that it can fasten itself to metatarsal III (39).

Top view of the left metatarsal bones of Elaphrosaurus bambergi (top = anterior, bottom = posterior). Janensch, Werner (1920). “Über Elaphrosaurus Bambergi und die Megalosaurier aus den Tendaguru–Schichten Deutsch–Ostafrikas”. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin (1920). Page 228.

Top view of the left metatarsal bones of Nedcolbertia: K = CEUM 5071; L = CEUM 5072. Kirkland, James I.; Britt, Brooks B.; Whittle, Christopher H.; Madsen, Scott K.; Burge, Donald L. (1998). “A small coelurosaurian theropod from the Yellow Cat Member of the Cedar Mountain Formation (Lower Cretaceous, Barremian) of eastern Utah”. New Mexico Museum of Natural History and Science Bulletin, volume 14 (1998). Page 246.

Conclusion – Is Nedcolbertia an Elaphrosaur: Yes or No?
Elaphrosaurs are curious animals because their anatomy contains a hodge-podge of physical features which are typically found within other dinosaur groups. This supports the idea that they come from a primitive lineage before dinosaurs branched off into numerous sub-divisions. Because elaphrosaurs share “synapomorphies” with several different dinosaur clades, it can sometimes be difficult to establish their true identity.

Well, what about the enigmatic Nedcolbertia of western North America? Was it a coelurosaur, as it was originally identified? Or was is an ornithomimosaur, as was proposed in 2017? Or could it actually be an elaphrosaur?

While Nedcolbertia does indeed share similar anatomical features with elaphrosaurs such as Elaphrosaurus and Limusaurus, in the end it must be said that, no, it is not an elaphrosaur. It is, in fact, a very primitive very archaic ornithomimosaur, which is exactly what Chase Brownstein said it was back in 2017. Examination of the structure of its lower leg bones, the size of its arm bones, and the size of its hand claws prove that this animal was not an elaphrosaur. Elaphrosaurs had differently-arranged metatarsal bones, they had short spindly arms, and possessed tiny hands with short stubby claws. Nedcolbertia had none of those features.

No skull of Nedcolbertia is currently known. However, since it was a primitive member of the ornithomimosaur group, it’s very likely that its jaws still had tiny teeth, like the Spanish ornithomimosaur Pelicanimimus or the Chinese ornithomimosaur Shenzhousaurus. Pelicanimimus which lived about 130 MYA, had both its upper and lower jaws lined with hundreds of tiny teeth, forming a flamingo-like sieve (40). The primitive ornithomimosaur Shenzhousaurus which was found within the lowermost part of the Yixian Formation of Liaoning Province, China, dated 139-128 MYA, had teeth only within the front of its lower jaw, with its upper jaw being entirely toothless (41). Did Nedcolbertia have feathers? Certainly. Were those feathers as well-developed as those seen in later more-derived ornithomimosaurs? Maybe, then again, maybe not.

If you have read through this entire article hoping that I would be providing conclusive proof to support my hypothesis, then I apologize for wasting your time. “Negative result” papers are rare in science, where a hypothesis is proposed and the conclusions show that the hypothesis proved to be completely wrong. However, I wish to state that even though I didn’t come up with the results that I was hoping for, it does nevertheless add to the overall picture and give us a clearer understanding of what these animals were like. I also like to think that I just saved some poor paleontology graduate student from wasting their time on a dead-end research project. If you’re out there…you’re welcome.

Below is an illustration which I made of what Nedcolbertia might have looked like. Since no skull of Nedcolbertia is known, the shape of the head is based upon a combination of the heads of the primitive ornithomimisaurs Harpymimus, Pelicanimimus, and Shenzhousaurus. The black-and-white coloration and the inflatable turquoise-colored throat pouch are purely artistic fancy. The drawing was made on printer paper with No.2 pencil, No.3 pencil, Prismacolor colored pencils, and a lot of touching-up on my computer so that the image’s color and the crispness which you see here matched the real-life picture which I drew.

Nedcolbertia. © Jason R. Abdale (August 18, 2022).

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Websites
Phys.org. “Australia’s first elaphrosaur discovered in Victoria”, by Swinburne Museum of Technology (May 18, 2020).
https://phys.org/news/2020-05-australia-elaphrosaur-victoria.html. Accessed on February 24, 2022.

Prehistoric Wiki. “Angeac ornithomimosaur”.
https://prehistoric-wiki.fandom.com/wiki/Angeac_ornithomimosaur. Accessed on February 24, 2022.

Tetrapod Zoology. “Ostrich dinosaurs invade Europe! Or do they?”, by Darren Naish (June 3, 2014).
https://blogs.scientificamerican.com/tetrapod-zoology/ostrich-dinosaurs-invade-europe-or-do-they/. Accessed on February 21, 2022.

The Official PLOS Blog. “Stepping Out: New Ornithomimosaur from Arkansas Described”, by Ian Hamilton (March 27, 2018).
https://theplosblog.plos.org/2018/03/stepping-out-new-ornithomimosaur-from-arkansas-described/. Accessed on March 8, 2022.

Videos
Utah’s Dino Graveyard. The Science Channel, 2007.

YouTube. Tate Geological Museum. “Tate Geological Museum’s Spring Lecture Series 2021: Cretaceous Dinosaurs- part 3 – The Cedar Mountain Formation of Utah: North America’s Most Complete Early Cretaceous Record, hosted by James I. Kirkland” (May 11, 2021).
https://www.youtube.com/watch?v=Thhb6Jy-Acw. Accessed on March 10, 2022.

Categories: Paleontology, Uncategorized

Tags: Africa, America, art, Asia, Australia, Cedar Mountain Formation, Ceratosauria, ceratosaurid, Ceratosaurus, Cretaceous Period, dinosaur, Early Cretaceous, elaphrosaur, Elaphrosaurus, Europe, Jurassic Period, Late Jurassic, maniraptora, Mesozoic, Middle Cretaceous, Middle Jurassic, Nedcolbertia, noasaur, noasaurid, Noasauridae, North America, ornithomimid, ornithomimosaur, paleo-art, paleontology, Prehistoric, reptile, South America, theropod, Utah