New pterosaur hatchling video from Dr. Witton misinforms

A new video
from Dr. M. Witton looks at the possibility of gliding in hatchling pterosaurs. Unfortunately it is full of misinformation.

Distinct from what Dr. Witton is telling us,
pterosaur hatchling and juvenile proportions are not much different than their 8x larger adult forms. See link below and this growth series image: https://pterosaurheresies.wordpress.com/2015/12/15/pterodaustro-isometric-growth-series/

From the hatchling Pterodaustro image,
Dr. Witton has omitted the skull and neck, but it is present in the egg (it has to be!) and is nearly identical to that of the adult. We looked at a second embryo earlier here (Fig. 2), and for the first embryo see:  http://reptileevolution.com/pterodaustro-embryo.htm for details.
Figure 3. Rough reconstruction using color tracings. Note the elongate jaws and small eye, documenting isometric growth in this pterosaur, as in all others where this can be seen.

Figure 2. Rough reconstruction using color tracings. Note the elongate jaws and small eye, documenting isometric growth in this pterosaur, as in all others where this can be seen.

Relatively large hatchlings
were able to take flight shortly after hatching. True. The eggs were carried within the mother until ready to hatch, as in many lepidosaurs. The eggshell membrane is also lepidosaurian.
In direct contrast,
the fly-sized hatchllngs of tiny pterosaurs had to grow to a size at which they could leave their damp leaf litter environs, or suffer from desiccation based on their surface-to-volume ratio, as in the tiniest living lizards.  See: https://pterosaurheresies.wordpress.com/2011/08/11/the-tiniest-pterosaur-no-6/
Figure 4. Two of the smallest pterosaurs that both have a large sternal complex. BMNH42736 and B St 1967 I 276.

Figure 3. Two of the smallest pterosaurs that both have a large sternal complex. BMNH42736 and B St 1967 I 276.

Gliding is not an option
for baby pterosaurs hatching on the ground. Pterosaurs and their ancestors were flapping before they could fly. Gliding is an ability acquired later in large derived taxa, the same as in birds.
FIgure 8. Dimorphodon take off (with the new small tail).

FIgure 4. Dimorphodon take off (with the new small tail).

The quadrupedal launch
shown in several illustrations is not only bogus, but dangerous and inefficient for the pterosaur. Much better to use the giant flapping wing for thrust from the first moment of take-off. For details: https://pterosaurheresies.wordpress.com/2011/07/20/seven-problems-with-the-pterosaur-wing-launch-hypothesis/
Figure 8. A larger view of Nemicolopterus. Pedal digit 5 is relatively reduced here.

Figure 5. Nemicolopterus. This tiny taxon is close to Sinopterus, but closer to Shenzhoupterous. 

Dr. Witton discusses a Sinopterus dongi hatchling.
He is considering tiny adult Nemicolopterus (Fig. 5) a hatchling. The Nemicolopterus specimen has traits distinct from Sinopterus and nests separately in a cladogram closer to Shenzhoupterus, whereas all other adult/hatchling pairs nest together in a pterosaur cladogram. See: http://reptileevolution.com/nemicolopterus.htm
Figure 1. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen.

Figure 6. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen.

We know of not one, but two Pteranodon juveniles.
For details: http://reptileevolution.com/pteranodon-juvenile.htm
For all future and present paleontologists reading this blog.
It is vitally important that you back up your hypotheses with evidence. Don’t cherry-pick or cherry-delete data to fit your notions or fool an audience.
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Flugsaurier 2018: Los Angeles County Museum

Flugsaurier
is a meeting of those interested in pterosaurs that happens in another part of the world every few years. I went to the first few. Saw a lot of specimens. Met a lot of colleagues. Produced a few abstracts and gave some presentations.

Over the next few days
there’s a Flugsaurier meeting taking place in Los Angeles. Many well-known and not-so-well known speakers are giving presentations this year. I will not be among them. Why?

So far as I know,
all of the conveners and many of the presenters continue to ignore a paper I wrote 18 years ago on the origin of pterosaurs from fenestrasaurs, not archosaurs. Other papers followed on wing shape, trackmaker identification and other topics, all supporting that phylogenetic hypothesis of relationships. Evidently workers would prefer to hope that pterosaurs arose from archosaurs close to dinosaurs. This is not where the data takes anyone interested in the topic who is not a party to taxon exclusion.

In addition, several of the conveners

  1. subscribe to the invalid quad-launch hypothesis
  2. the bat-wing reconstruction of the brachiopatagium.
  3. they believe that pedal digit 5 framed a uropatagium.
  4. They refuse to add tiny Solnhofen pterosaurs to their cladograms.
  5. They refuse to add several specimens of each purported genus to cladograms—and because of this they don’t recognize the four origins of the pterodactyloid-grade (not clade).
  6. They still don’t recognize that pterosaurs grew isometrically.
  7. They still don’t accept that pterosaur mothers retained their egg/embryo within the body until just before hatching (a lepidosaur trait).
  8. They still don’t accept that pterosaur bone fusion patterns follow lepidosaur, rather than archosaur patterns.
  9. They accept the idea that giant eyeballs filled the anterior skulls of anurognathids, not realizing that the supposed ‘scleral ring’ on edge of the flathead anurognathid is actually the mandible and tiny teeth.
  10. They reject any notion that all basal and some derived pterosaurs were bipedal, despite the footprint and morphological evidence proving bipedal locomotion.
  11. They all hold out hope that the largest azhdarchids could fly.
  12. I was going to say that all workers believe that crest size and hip shape identify gender, when the evidence indicates these are both phylogenetic markers, but then I found an abstract in 2018 that casts doubt on the gender/crest/pelvis hypothesis. So there’s hope.

That’s a fairly long list of ‘basics’
that most pterosaur workers ‘believe in’ despite the fact that there is no evidence for these false paradigms — but plenty of evidence for the lepidosaur origin of pterosaurs, from which most of the above hypotheses follow.

I am not attending Flugsaurier 2018
because the convening pterosaur workers deny and suppress the data listed above. Plus, I can more actively and thoroughly test assertions made during the conference from ‘my perch’ here in mid-America.

Good luck to those attending. 
Test all assertions and hypotheses, no matter their source.

Hamipterus egg accumulation: Wang et al. 2017

Earlier
here and here we looked at the 3-D eggs of Hamipterus, a basal ornithocheirid from Early Cretaceous China. The eggs are scattered in and amongst a wide size/age range of disarticulated, but 3-D fossils. So, according to the authors, the eggs were buried, then bones and eggs were transported by storms, as if bulldozed. No embryos were reported from those eggs. No explanation why the pterosaurs did not fly away in the face of the storm, nor why more sediment wasn’t packed on the buried eggs during the storm.

Today
comes news from this expanding treasure trove site with embryo bones at several stages of development in 16 eggs out of hundreds! That’s good news because full-term embryos (= hatchlings) are identical to parents and eggs keep all the bones from an individual in a neat little package so we can finally put together what Hamipterus looked like.

But that’s not the picture the authors paint.
They said, “some bones lack extensive ossification in potentially late-term embryos, suggesting that hatchlings might have been flightless and less precocious than previously assumed.” Point-by-point:

  1. No nests were found.
  2. 215+ eggs were found
  3. Eggs appeared in moderate size variation
  4. The large number of accumulated eggs (Fig. 1) indicates they were laid by different females
  5. Some were subjected to differential water uptake during transport
  6. Internal content(?) observed in 42 eggs, 16 had embryos
  7. Bones not concentrated on the bottom half of the egg, as in dinosaurs
  8. No embryo is complete. One to several bones only in each of the 16 eggs.
  9. No teeth found in embryos.
  10. The most complete embryo had a lower jaw of 17mm. That’s 4% the size of the largest adult when other full-term pterosaur embryos are 12.5% (1/8) at hatching. So these were not full-term embryos ready to hatch.
  11. In a 2.2m section, eight layers with pterosaur bones have been identified, four of which show egg concentrations in a vertical distance of 1.4 m.

The authors note and conclude:
“This suggests that the hind limbs have developed more rapidly compared to the forelimbs and might have been functional right after the animal hatched. Thus, newborns were likely to move around but were not able to fly, leading to the hypothesis that Hamipterus might have been less precocious than advocated for flying reptiles in general (6) and probably needed some parental care.”

No. Think again.
Pterosaur mothers carried their eggs inside their bodies until just before hatching. That gives their babies warmth and protection until they are ready to hatch. They could do this because they are lepidosaurs, as phylogenetic analysis AND egg shell thickness and pliability tells us.

Figure 1. From Wang et al. 2017, a pterosaur egg and bone accumulation. Eggs float. So do hollow pterosaur bones.

Figure 1. From Wang et al. 2017, a pterosaur egg and bone accumulation. Eggs float. So do hollow pterosaur bones.

Sedimentology report:
“This sedimentological data, associated with the exceptional quantity of eggs and bones, indicate that events of high energy such as storms have passed over a nesting site, causing the eggs to be moved inside the lake where they floated for a short period of time, becoming concentrated and eventually buried along with disarticulated skeletons.”

Bottom line and biggest problem:
The authors assume the eggs were laid. That’s because they think pterosaurs are archosaurs. Birds and crocs are archosaurs and they lay their eggs at an early stage of fertilization. Lepidosaurs wait to lay their eggs, sometimes until the moment before hatching.

Alternative hypothesis:

  1. Mass death of several year-classes of pterosaurs on beach due to lake burping deadly carbon dioxide. That stops the parents from flying away.
  2. Desiccation and insect decomposition reveals eggs inside of female skeletons. This takes just a few days to a week and allows skeletons to easily separate into individual bones (Fig. 1)
  3. Later rising waters (storms optional, melting snow pack will do), overwhelms beached skeletons and exposed eggs. Even a few extra inches of water would be enough for this.
  4. Eggs float. So do pterosaur bones
  5. Wind/ripples push eggs and bones together back against beach bank corner where they accumulate. (This happened several times over dozens to hundreds of years, but not annually.)
  6. Water recedes leaving eggs en masse along with settling disarticulated individual bones of parents and kin
  7. Burial process is later completed with airborne or waterborne sediments overwhelming the bones and eggs in situ.
  8. To point #3 above: moderate egg size variation, we also see this in the chicken eggs we get at our local grocery, but pterosaurs kept growing throughout their lives and larger ones would tend to lay bigger eggs, though this has not been conclusively demonstrated, it seems broadly logical.

Evidently
the lake burping did not always coincide with the pterosaurs flocking together. But it happened four times to a portion of the flock, perhaps over hundreds of years, and evidently at ‘the back of the room where bad things happen’.

References
Wang X and 16 co-authors 2017. Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science 358:1197–1201.

Pterodaustro embryo goes under DGS

Codorniú et al. 2017.
bring us detailed images of a wonderful Pterodaustro embryo (MIC-V246, Early Cretaceous; Chiappe et al. 2004) we’ve seen before. Here (Figs. 1–3) we’ll take a closer look at the fossil itself using DGS to untangle it. This is the same embryo first described by Chiappe et al. 13 years ago. Why did it take so long to bring out these details? There’s nothing really new here, no revision to their original description.

Figure 1. Pterodaustro embryo from Codorniú et al. with DGS color overlays to graphically segregate bones from one another.

Figure 1. Pterodaustro embryo from Codorniú et al. with DGS color overlays to graphically segregate bones from one another. Compare original reconstruction here to that in Figure 3.  Note the broken tibiae. Look how much better color over a photo works than pen and ink.

Turn out
the embryo is far less disarticulated than originally considered. Several bones are newly identified here (Fig. 2).

Figure 2. Original interpretations (2 frames black/white) vs. new interpretations (color).

Figure 2. Original interpretations (2 frames black/white) vs. new interpretations (color).

What Codorniú et al identified as

  1. ascending process of the premaxilla (pmx) is here a right metacarpal 4 (mc4)
  2. right wing phalanx 4 (wp4) is here a maxilla (mx) and premaxilla (pmx)
  3. left metacarpal 4 (mc4) is here a proximal radius (ra)
  4. left coracoid (co) is here a left metacarpal 4 (mc4)
  5. dorsal vertebrae (dv) and ribs at top is here identified as cervical vertebrae and left metacarpals 1–3).
  6. jugal (ju) and maxilla (mx) are here identified as mandible and palatal elements, but there’s also a short jugal in there below the sclerotic ring
  7. right metacarpal 4 (mc4) is here identified as a left scapula
  8. right wing phalanx 1 (wp1) is here identified as a left coracoid
  9. right wing phalanx 2 (wp2) is here identified as a dentary portion + left wp3 (4.3).
  10. gastralia (ga) are here identified as left dorsal ribs with tiny gastralia below
  11. caudal vertebrae (ca) here identified as possible sacral ribs

Parts missing from the Codorniú et al. tracing, but recovered using DGS include

  1. dozens of teeth
  2. prepubes
  3. pteroids
  4. carpals
  5. sternal complex
  6. finger phalanges including wing tip ungual (4.5)
  7. sclerotic rings
  8. cranial bones (parietals + occipitals)
  9. caudal vertebrae
  10. proximal femora
Figure 2. Same as in figure 1 with elements segregated.

Figure 3. Same as in figure 1 with elements segregated. Just a little bit of eggshell is preserved and it is very thin.

Digital Graphic Segregation (DGS)
is the perfect tool to interpret a fossil such as this. Embryos are encased in eggshell. That means every bone is retained in a small area, undisturbed by invaders or currents. Most embryos are going to be articulated, barring violent shaking, which could happen if the egg was tumbled and/or dropped. Some bones will just barely appear below others.

Try DGS yourself.
First color the bones that are easy to identify. Segregate the wings from other skeletal elements. Then color in all the remaining bones, including those that barely appear below other elements. Finally, lift your colors to another file and push them around to create a reconstruction. Check your work for errors and repeat.

Figure 3. Rough reconstruction using color tracings. Note the elongate jaws and small eye, documenting isometric growth in this pterosaur, as in all others where this can be seen.

Figure 4. Rough reconstruction using color tracings. Note the elongate jaws and small eye, documenting isometric growth in this pterosaur, as in all others where this can be seen. Note the relatively short tibia. This could be longer, but pars are hidden by the feet and other bones.

The thin egg shell
is similar to those in lepidosaurs because pterosaurs are lepidosaurs. As lepidosaurs mothers can carry their eggs until just before hatching, taking advantage of her warmth and her ability to avoid predators. Please ignore hypotheses that suggest pterosaurs buried their eggs. No fragile hatchling wants to dig out of a deep steaming pile of wet, rotting leaves filled with insects and centipedes. They’re not like husky little sea turtles. Baby pterosaurs want to dry out, open up their tiny wings and fly!

Pterodaustro adult with manual digit 3 repaired.

Figure 4. Pterodaustro adult with manual digit 3 repaired.

At one-eigth the size of a typical adult (which also vary in size)
embryo Pterodaustro was similar in proportions, but with shorter tibiae, smaller feet, more gracile jaws and other minor differences. With such proportions, there is nothing to prevent hatchling Pterodaustro from flying.

Figure 2. Pterodaustro embryos compared. Note the 2004 specimen is a little larger with more robust wing finger phalanges and a larger sternal complex.

Figure 2. Pterodaustro embryo compared to post-hatchling. Note the right specimen is a little larger with more robust wing finger phalanges and a larger sternal complex.

We looked at other pterosaur embryos
here, here, here, here, and here.

Bone fusion patterns in pterosaurs
Codorniú et al. discuss the lack of scapulacoracoid (s/c) bone fusion in the embryo and considered that an ontogenetic trait. A long time ago, bone fusion was phylogenetically mapped on the pterosaur cladogram. No current embryos have s/c bone fusion, but then neither do any of their adults or sisters. What we need is to find an embryo of a pterosaur genus with a fused s/c as an adult. We have not found one yet. As lepidosaurs, pterosaurs follow lepidosaur bone fusion patterns (Maisano 2002), which are phylogenetic, not ontogenetic. Fused bones keep growing. So do unfused bones into adulthood.

It would be great
if this embryo finally puts to rest the invalid hypothesis of allometric growth in pterosaurs promoted by Bennett and many Bennett followers who considered small, short rostrum, large-eyed Solnhofen pterosaurs the juveniles of larger, longer-snouted specimens. Zhejiangopterus and Pterodaustro growth series provide further strong evidence against the invalid allometric growth hypothesis. Pterosaur workers: GET OVER IT! IT’S WRONG!

References
Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Chiappe LM, Codorniú L, Grellet-Tinner G and Rivarola D. 2004. Argentinian unhatched pterosaur fossil. Nature, 432: 571.
Codorniú L, Chiapped L and Rivarola D 2017. Neonate morphology and development in pterosaurs: evidence from a Ctenochasmatid embryo from the Early Cretaceous of Argentina. From: Hone DWE, Witton MP and Martill DM (eds) New Perspectives on Pterosaur Palaeobiology. Geological Society, London, Special Publications, 455, https://doi.org/10.1144/SP455.17
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.

 

 

Dr. David Unwin on pterosaur reproduction – YouTube

Dr. David Unwin’ talk on pterosaur reproduction 
was recorded at the XIV Annual Meeting of the European Association of Vertebrate Palaeontologists, Teylers Museum, Haarlem, Netherlands and are online as a YouTube video.
Dr. Unwin is an excellent and engaging speaker.
However, some of the issues Dr. Unwin raises have been solved at www.ReptileEvolution.com
The virtual lack of calcite in pterosaur eggs were compared to lepidosaurs by Dr. Unwin, because pterosaurs ARE lepidosaurs.  See: www.ReptileEvolution.com/reptile-tree.htm
Lepidosaurs carry their eggs internally much longer than archosaurs, some to the point of live birth or hatching within hours of egg laying. Given this, pterosaurs did not have to bury their eggs where hatchlings would risk damaging their fragile membranes while digging out. Rather mothers carried them until hatching. The Mrs. T external egg was prematurely expelled at death, thus the embryo was poorly ossified and small.
Dr. Unwin ignores the fact that hatchlings and juveniles had adult proportions as demonstrated by growth series in Zhejiangopterus, Pterodaustro and all others, like the JZMP embryo (with adult ornithocheirid proportions) and the IVPP embryo (with adult anurognathid proportions).
Dr. Unwin also holds to the disproved assumption that all Solnhofen sparrow- to hummingbird-sized pterosaurs were juveniles or hatchlings distinct from any adult in the strata. So they can’t be juveniles (see above). Rather these have been demonstrated to be phylogenetically miniaturized adults and transitional taxa linking larger long-tailed dorygnathid and scaphognathid ancestors to larger short-tailed pterodactyloid-grade descendants, as shown at: www.ReptileEvolution.com/MPUM6009-3.htm
Thus the BMNH 42736 specimen and Ningchengopterus are adults, not hatchlings. And the small Rhamphorhynchus specimens are also small adults.

Rhamphorhynchus n28: unidentified food mass? or overlooked egg in the abdomen?

Figure 1. Rhamphorhynchus intermedius (n28) reconstructed.

Figure 1. Rhamphorhynchus intermedius (n28) reconstructed.

Rhamphorhynchus intermedius (Koh 1937, n28 in the Wellnhofer 1975 catalog) is a well preserved basal specimen (derived from the C3 specimen of Campylognathoides) with a mass inside of its torso, only part of which has been identified as a Solhnhofen fish (Figs. 2,3).

Figure 2. Wellnhofer 1991 illustrates the abdominal mass as part of a fish and other unidentified elements.

Figure 2. Wellnhofer 1991 illustrates the abdominal mass as part of a fish and other unidentified elements.

The rest of the abdominal mass
is unidentified (Fig. 2). Wellnhofer 1991 considered it food. Considering its shape, size and placement, I wonder if the posterior mass is actually a nearly full term egg (Fig. 3). I don’t think it makes much sense to consider such an abdominal mass as “unidentified food” when no other known specimen has a similar mass of undigested food. That would mean the stomach could expand to fill the abdomen. Usually the only thing that crowds out other organs and air sacs is an egg or a number of eggs in other reptile taxa. Check out this kiwi X-ray for an extreme example.

Figure 3. Skeletal elements of Rhamphorhynchus intermedius (n28) along with an ingested fish and what appears to be a possible egg.

Figure 3. Skeletal elements of Rhamphorhynchus intermedius (n28) along with an ingested fish and what appears to be a possible egg. Note the overlapping sets of gastralia. It looks like the jaws of the fish are displaced here. Wellnhofer did not see the large eyeball identified here. Note the left scapula and coracoid are inverted. There sternal complex has a similar unexpectedly bumpy texture as the purported egg.

Rhamphorhynchus intermedius
is a medium-sized Rhamphorhynchus nesting at the very base of the clade between the larger Campylognathoides and the smaller Bellubrunnu. Thus it is a transitional taxon, step one in an extreme example of phylogenetic miniaturization. No one understood this nesting prior to the phylogenetic analysis documented at ReptileEvolution.com because no one included a long list of Rhamphorhynchus specimens in analysis prior to or since. I’d like to encourage other pterosaur workers to do so and test this hypothesis of relationships.

Texture
The “egg” has an odd texture, but then so does the sternal complex. Not sure why.

Previous examples?
Two smaller examples of “something else” in the abdomen of – or just aborted from the abdomen – other specimens of Rhamphorhynhcus can be seen here and here.

References
Koh TP 1937. Unterscuchungen über die Gattung Ramphorhynchus. – Neues Jahrbuch Mineralogie, Geologie und Palaeontologie, Beilage-Band 77: 455-506.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33. Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

Another look at the tiny pterosaur, Nemicolopterus

Not content
with a fully resolved cladogram, I wanted higher Bootstrap scores at certain nodes to ascertain nesting pairs. So I reviewed the data for several taxa, among them Nemicolopterus. I found mistakes and oversights, nearly all of which more closely match Nemicolopterus to its much taller sister, Shenzhoupterus (Fig. 1) within the larger encompassing Germanodactylus/Tapejara clade.

Figure 1. Germanodactylus cristatus and members of the Shenzhoupteridae, Nemicolopterus and Shenzhoupterus.

Figure 1. Germanodactylus cristatus and members of the Shenzhoupteridae, Nemicolopterus and Shenzhoupterus.

When first announced
(Wang et al. 2008), Nemicolopterus was hailed as the smallest, or one of the smallest known pterosaurs. And it is. But there is one other that is only half as tall (Fig. 2) which we looked at in more detail yesterdayB St 1967 I 276.

Figure 2. Nemicolopterus has been described as the smallest pterosaur, but No. 6 in the Wellnhofer (1970) catalog was only half as tall.

Figure 2. Nemicolopterus has been described as the smallest pterosaur, but B St 1967 I 276, No. 6 in the Wellnhofer (1970) catalog was only half as tall.

An insitu tracing 
animated in a GIF movie reveals the bones segregated by digital layers (Fig. 3).

Figure 3. Two images of Nemicolopterus superimposed and traced with transparent colors. Note, not all of the shapes seen in photo 1 can be seen in photo 2. There appear to be extra tiny bones in the belly of this specimen.

Figure 3. Two images of Nemicolopterus superimposed and traced with transparent colors. Note, not all of the shapes seen in photo 1 can be seen in photo 2. There appear to be extra tiny bones in the belly of this specimen where all the ribs and gastralia have been accounted for. Click to enlarge. 

A displaced sliver of bone in the cheek
would appear to be the ventral portion of an orbit-dividing lacrimal, as in sister taxa. No one would identify this bone as such without phylogenetic bracketing. Hairlike soft tissue arising from the rostrum evidently precedes the rostral crest found in Shenzhoupterus. The free fingers remain unknown.

Phylogenetic miniaturization 
appears to be at work once again with Nemicolopterus, a tiny adult at the base of a major clade or two of pterosaurs in the large pterosaur tree.

References
Wang X, Kellner AWA, Zhou Z and Campos DA 2008. Discovery of a rare arboreal forest-dwelling flying reptile (Pterosauria, Pterodactyloidea) from China. Proceedings of the National Academy of Sciences, 106(6): 1983–1987. doi:10.1073/pnas.0707728105

wiki/Nemicolopterus