The Platypus, Part 4

The cast of a skull of the extinct platypus Obdurodon. The two arrows are pointing at molars, which help distinguish this platypus from the living genus. Picture modified from a picture by Skye M, obtained from Wikimedia Commons.

In this last post, I want to put the platypus in another context. We have seen how it is unique among extant mammals with a few features that more closely resemble what is found in non-mammals (such as the shoulder girdle, the cloaca, and the electroreceptors). As it turns out, the platypus is not that strange compared to other mammals. It is just that the variety of mammals alive today is much less than it was before the Flood. Placentals are such a prominent part of mammal diversity today that we tend to think of placentals as “normal” and that anything that deviates from them is unusual. If we look at the fossil record, we actually find that some of the unique traits of the platypus were found in other mammals as well.

Let us begin by looking at fossils of platypuses specifically. Most fossil platypus belong to the genus Obdurodon. This genus resembled the extant platypus, differing primarily in two ways. First, the three Obdurodon species are larger than Ornithorhynchus, the living platypus. Second, Obdurodon retained their molars as adults. It was mentioned in the last post that the living platypus does not have molars, it has grinding plates. Technically, young platypuses have molars which are eventually replaced by the grinding plates. Obdurodon, in contrast, retains its molars as an adult.

There is some variation in molar shape among the three species of Obdurodon. Some appear to be better at cutting, some better at grinding.[1] While the three species of Obdurodon probably all had a similar lifestyle to Ornithorhynchus, their molars indicate that they consumed different types of prey.

One species of Obdurodon, Obdurodon tharalkooschild, is considered to be a giant among platypuses. The exact size is not known, since it is based on fragmentary remains, but it is believed to have exceeded 28 inches in length.[2] Of course, 28 inches may not seem that large, but considering that a very large living male may get to be 24 inches long, with the average being closer to 18 inches,[3] greater than 28 inches is indeed large.

The genus Obdurodon is found, surprise surprise, exclusively in Australia. However, the three Obdurodon species are not the only known platypus fossils. There is a fourth fossil platypus species and it is Monotrematum sudamericanum. It is based on some fragmentary remains, but it is estimated to be about 28 inches long, so pretty large for a platypus. Its remains are found in, get ready for it…

Patagonia, Argentina.[4]

That’s right: Monotrematum is a fossil platypus from South America. It shows that platypuses are not exclusively Australian. It is especially interesting to note that Monotrematum is the lowest occurrence of platypus fossils, meaning it is found deepest in the fossil record. Perhaps, and this is just a suggestion on my part, perhaps Monotrematum is a pre-Flood platypus and Obdurodon fossils are post-Flood fossils. It would neatly explain how the platypus “jumped” from one hemisphere to another.

There are a couple of more fossils that relate to platypuses. These are Teinolophus and Steropodon. Both of these fossils are fragmentary, from Australia, and from Cretaceous rocks. They have also been interpreted as platypuses[5] but are generally regarded as monotremes that lie outside of the families Ornithorhynchidea (the platypus family) and Tachyglossidae (the echidna family).[6] What both Teinolophus and Steropodon show us is that monotremes used to be more diverse and probably contained more families than the platypus and echidnas. Imagine how much more “common” the platypus would be if there was a greater variety of monotremes.

Ornithorhynchidae, Tachyglossidae, Teinolophus, and Steropodon represent the extent of the known types of monotremes. There are a few more fragmentary remains that have been identified as monotremes, but that is about it. In case you are wondering, there are known fossils of echidnas,[7] but they belong to the Tachyglassidae family and probably resembled living echidnas, much as the fossil platypuses resemble the extant platypus. However, there are a few more types of fossils that I want to consider before we wrap up this series on the platypus.

A few posts ago, I highlighted that there are three types of mammals: placentals, marsupials, and monotremes. While that separation works for mammals that are alive today, it does not work so well with many fossil mammals. There are a number of fossil mammals, most of which come from Mesozoic rocks,[8] that are neither placental, marsupial, nor monotreme. In fact, aside from the monotremes Teinolophus and Steropodon, almost every single mammal from Mesozoic rocks lies outside of the placental/marsupial/monotreme trichotomy. Let us take a brief survey of some of these mammals, to get a better idea of the former diversity of mammals.

The skull of Repenomamus. Note that there is no distinct fang in the mouth. Rather, it was about the same size and shape as the incisors. Image from Hu, Yaoming, Jin Meng, Yanqing Wang, and Chuankui Li (2005) “Large Mesozoic mammals fed on young dinosaurs” Nature 433: 149-152.

Let us first consider Repenomamus. This mammal has been variously compared to a badger[9] and a tasmanian devil.[10] It is neither. Instead, it belongs to a family called Gobiconodontidae within a larger group called Eutricodonta.[11] There are two species of Repenomamus: Repenomamus robustus and Repenomamus giganticus. The latter is about twice the size of the former, and with a length of over three feet and a weight comparable to that of an American badger, Repenomamus giganticus is considered the largest known mammal from Mesozoic rocks. Repenomamus was known to be a carnivore (it is probably most famous for a specimen that contains the remains of a baby dinosaur in its stomach) but its tooth arrangement was different from most carnivorous mammals. Rather than having short incisors and long canines, the canines and incisors of Repenomamus were all of the same size and shape. These teeth lined the front of the jaws, allowing the animal to snag potential prey. Unlike the platypus which sprawls, Repenomamus had a semi-errect posture, which would be more similar to the posture of a rat or a badger. However, compared to most placental mammals, it had a longer torso and shorter, sturdier legs.[12] Thus, we can see that, much like the platypus, Repenomamus was its own unique type of mammal and not a mere carbon copy of an extant mammal.

A reconstruction of Volaticotherium. Image fr

Another interesting Mesozoic mammal is Volaticotherium. This little mammal is notable for being a gliding mammal: traces of a furry patagium (stretched skin between the legs) were found preserved with the skeleton. As a gliding mammal, it was probably reminiscent of a flying squirrel. However, what helps set it apart from most other mammals are its teeth. The incisors and canines are rather typically of mammals: incisors are short, round, and pointy and the canines are long and sharp. The molars, however, have multiple cusps (sharp ridges) that all sweep toward the back of the mouth. This gives the molars the appearance of a comb with curved teeth. This dentition was probably used for eating insects. Volaticotherium is unique enough that it is not only put in its own family (Volaticotheriidae), it is also put in its own order (Volaticotheria).[13]

One final fossil mammal to talk about it Castorocauda, a name that translates into “beaver tail.” The reason is because this small aquatic mammal had a tail much like a beaver. It was broad and flat and even had scales, making it even more beaver-like than the tail of a platypus. Like a platypus, it had sprawling limbs. The forelimbs, in particular, were rather similar to a platypus and were thought to have been used for both swimming and burrowing. The shoulder girdle is also similar to a platypus’s, containing several bones making it stiffer and sturdier than most mammals. The head was rather generic for a small mammal, being rather long and conical (think of a rat’s head in general shape). However, the ear bones of Castorocauda is unlike any found in living mammals. Several of the ear bones are associated with and attached to the lower jaw. In a typical mammal, the lower jaw consists of a single bone (the dentary). In addition, there are three bones in the middle ear: the malleus, incus, and stapes. In Castorocauda, the malleus is actually attached to the dentary through another bone called the surangular. Even though it was attached to the lower jaw, the malleus was probably still involved in hearing. It probably still conducted sound to the incus and stapes. Now, this arrangement is not unique to Castorocauda: it was probably typical of the order Docodonta, which is the order that contains Castorocauda.[14] In fact, there were many types of mammals that had some of their ear bones attached to their lower jaw. It is thought that many of them actually heard sounds, at least partially, through the lower jaw, which would be effective for small, low slung animals that held their heads close to the ground (they would effectively “hear” vibrations coming through the ground).[15] 

These three examples, Repenomamus, Volaticotherium, and Castorocauda, is just a small sample. There were many other types of mammals that fall outside of the groups monotreme, marsupial, and placetal. Other examples include the orders Multituberculata, Haramiyida, and Morganucodonta.

To reiterate, all of these mammals that we have been highlighting come from Mesozoic rocks. As Mesozoic rocks are almost universally agreed by creationists to have been laid down during the Flood, we can safely surmise that these descriptions give us a small glimpse of the pre-Flood diversity of mammals. Since there is barely a trace of these types of mammals in rocks above the Cretaceous, we can conclude that, while they must have been taken aboard the Ark, they probably died out shortly after the Flood.

The loss of this diversity of mammals has severely limited our understanding of the nature of mammals. Placentals so thoroughly dominate mammal diversity today that anything that is not a placental is considered strange, hence why the special, unique platypus gets described as a hodge-podge of various animals. In a world where the Mesozoic animals were still alive, the platypus would seem a lot less strange. Thus, rather than relegating it as an oddball mixture of creatures, we should soberly celebrate it as a remnant of a diversity that has since been lost due to the wickedness of man.Now, I know that “soberly celebrate” is an oxymoron, but I mean it in the same way that a funeral is a mournful event but still a time to celebrate a person’s life. We can celebrate the uniqueness of the platypus, but rather than treating it as a one-off weird-for-the-sake-of-weirdness creature, we can remind ourselves that there used to be many more varieties of mammals, and that much of that staggering variety died off shortly after the Global Flood, which was sent as a punishment due to the wickedness of man. As such, the platypus can be seen as a remnant of a bygone era, not of a prior period of deep time, as the evolutionists do, but rather as a reminder of the diversity of creatures God designed for His original creation.

Thoughts from Steven.


[1]Pian, Rebecca; Micahel Archer; Suzanne Hand (2013) “A new, giant platypus, Obdurodon tharalkooschild, sp. nov. (Monotremata, Ornithorhynchidae), from the Riversleigh World Heritage Area, Australia” Journal of Vertebrate Paleontology 33(6):1255-1259

[2]Ibid.

[3]Grant, Tom (2013) Platypus, CSIRO Publishing, Collingwood, Australia, pg. 5

[4]Musser, A. M. (2003) “Review of the monotreme fossil record and comparison of palaeontological and molecular data” Comparative Biochemistry and Physiology Part A, 136:927-942

[5]Rowe, Timothy; Thomas Rich; Patricia Wickers-Rich; Mark Springer; Michael Woodburne (2008) “The oldest platypus and its bearing on divergence timing of the platypus and echidna clades” Proceedings of the National Academy of Sciences 105(4):1238-1242

[6]Phillips, Matthew; Thomas Bennett; Michael Lee (2009) “Molecules, morphology, and ecology indicate a recent, amphibious ancestry for echidnas” Proceedings of the National Academy of Sciences 106(4):17089-17094

[7]Musser, A. M. (2003) “Review of the monotreme fossil record and comparison of palaeontological and molecular data” Comparative Biochemistry and Physiology Part A, 136:927-942

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Preview(opens in a new tab)about:blankParagraph: Change block type or styleChange text alignmentAdd titleThe Platypus, Part 4

This image has an empty alt attribute; its file name is platypus-img6.jpg
The cast of a skull of the extinct platypus Obdurodon. The two arrows are pointing at molars, which help distinguish this platypus from the living genus. Picture modified from a picture by Skye M, obtained from Wikimedia Commons.

In this last post, I want to put the platypus in another context. We have seen how it is unique among extant mammals with a few features that more closely resemble what is found in non-mammals (such as the shoulder girdle, the cloaca, and the electroreceptors). As it turns out, the platypus is not that strange compared to other mammals. It is just that the variety of mammals alive today is much less than it was before the Flood. Placentals are such a prominent part of mammal diversity today that we tend to think of placentals as “normal” and that anything that deviates from them is unusual. If we look at the fossil record, we actually find that some of the unique traits of the platypus were found in other mammals as well.

Let us begin by looking at fossils of platypuses specifically. Most fossil platypus belong to the genus Obdurodon. This genus resembled the extant platypus, differing primarily in two ways. First, the three Obdurodon species are larger than Ornithorhynchus, the living platypus. Second, Obdurodon retained their molars as adults. It was mentioned in the last post that the living platypus does not have molars, it has grinding plates. Technically, young platypuses have molars which are eventually replaced by the grinding plates. Obdurodon, in contrast, retains its molars as an adult.

There is some variation in molar shape among the three species of Obdurodon. Some appear to be better at cutting, some better at grinding.[1] While the three species of Obdurodon probably all had a similar lifestyle to Ornithorhynchus, their molars indicate that they consumed different types of prey.

One species of Obdurodon, Obdurodon tharalkooschild, is considered to be a giant among platypuses. The exact size is not known, since it is based on fragmentary remains, but it is believed to have exceeded 28 inches in length.[2] Of course, 28 inches may not seem that large, but considering that a very large living male may get to be 24 inches long, with the average being closer to 18 inches,[3] greater than 28 inches is indeed large.

The genus Obdurodon is found, surprise surprise, exclusively in Australia. However, the three Obdurodon species are not the only known platypus fossils. There is a fourth fossil platypus species and it is Monotrematum sudamericanum. It is based on some fragmentary remains, but it is estimated to be about 28 inches long, so pretty large for a platypus. Its remains are found in, get ready for it…

Patagonia, Argentina.[4]

That’s right: Monotrematum is a fossil platypus from South America. It shows that platypuses are not exclusively Australian. It is especially interesting to note that Monotrematum is the lowest occurrence of platypus fossils, meaning it is found deepest in the fossil record. Perhaps, and this is just a suggestion on my part, perhaps Monotrematum is a pre-Flood platypus and Obdurodon fossils are post-Flood fossils. It would neatly explain how the platypus “jumped” from one hemisphere to another.

There are a couple of more fossils that relate to platypuses. These are Teinolophus and Steropodon. Both of these fossils are fragmentary, from Australia, and from Cretaceous rocks. They have also been interpreted as platypuses[5] but are generally regarded as monotremes that lie outside of the families Ornithorhynchidea (the platypus family) and Tachyglossidae (the echidna family).[6] What both Teinolophus and Steropodon show us is that monotremes used to be more diverse and probably contained more families than the platypus and echidnas. Imagine how much more “common” the platypus would be if there was a greater variety of monotremes.

Ornithorhynchidae, Tachyglossidae, Teinolophus, and Steropodon represent the extent of the known types of monotremes. There are a few more fragmentary remains that have been identified as monotremes, but that is about it. In case you are wondering, there are known fossils of echidnas,[7] but they belong to the Tachyglassidae family and probably resembled living echidnas, much as the fossil platypuses resemble the extant platypus. However, there are a few more types of fossils that I want to consider before we wrap up this series on the platypus.

A few posts ago, I highlighted that there are three types of mammals: placentals, marsupials, and monotremes. While that separation works for mammals that are alive today, it does not work so well with many fossil mammals. There are a number of fossil mammals, most of which come from Mesozoic rocks,[8] that are neither placental, marsupial, nor monotreme. In fact, aside from the monotremes Teinolophus and Steropodon, almost every single mammal from Mesozoic rocks lies outside of the placental/marsupial/monotreme trichotomy. Let us take a brief survey of some of these mammals, to get a better idea of the former diversity of mammals.

This image has an empty alt attribute; its file name is platypus-img7.jpg
The skull of Repenomamus. Note that there is no distinct fang in the mouth. Rather, it was about the same size and shape as the incisors. Image from Hu, Yaoming, Jin Meng, Yanqing Wang, and Chuankui Li (2005) “Large Mesozoic mammals fed on young dinosaurs” Nature 433: 149-152.

Let us first consider Repenomamus. This mammal has been variously compared to a badger[9] and a tasmanian devil.[10] It is neither. Instead, it belongs to a family called Gobiconodontidae within a larger group called Eutricodonta.[11] There are two species of Repenomamus: Repenomamus robustus and Repenomamus giganticus. The latter is about twice the size of the former, and with a length of over three feet and a weight comparable to that of an American badger, Repenomamus giganticus is considered the largest known mammal from Mesozoic rocks. Repenomamus was known to be a carnivore (it is probably most famous for a specimen that contains the remains of a baby dinosaur in its stomach) but its tooth arrangement was different from most carnivorous mammals. Rather than having short incisors and long canines, the canines and incisors of Repenomamus were all of the same size and shape. These teeth lined the front of the jaws, allowing the animal to snag potential prey. Unlike the platypus which sprawls, Repenomamus had a semi-errect posture, which would be more similar to the posture of a rat or a badger. However, compared to most placental mammals, it had a longer torso and shorter, sturdier legs.[12] Thus, we can see that, much like the platypus, Repenomamus was its own unique type of mammal and not a mere carbon copy of an extant mammal.

This image has an empty alt attribute; its file name is platypus-img8.jpg
A reconstruction of Volaticotherium. Image from Meng, Jin, Yaoming Hu, Yuanqing Wang, Xiaolin Wang, and Chuankui Li (2006) “A Mesozoic gliding mammal from Northeastern China” Nature 444:889-893.

Another interesting Mesozoic mammal is Volaticotherium. This little mammal is notable for being a gliding mammal: traces of a furry patagium (stretched skin between the legs) were found preserved with the skeleton. As a gliding mammal, it was probably reminiscent of a flying squirrel. However, what helps set it apart from most other mammals are its teeth. The incisors and canines are rather typically of mammals: incisors are short, round, and pointy and the canines are long and sharp. The molars, however, have multiple cusps (sharp ridges) that all sweep toward the back of the mouth. This gives the molars the appearance of a comb with curved teeth. This dentition was probably used for eating insects. Volaticotherium is unique enough that it is not only put in its own family (Volaticotheriidae), it is also put in its own order (Volaticotheria).[13]

Reconstruction of the body and skeleton of Castorocauda. You can compare the appearance of the forelimbs and shoulder girdle of this animal to that of the platypus, which can be seen in previous posts. Image from Ji, Qiang, Zhe-Xi Luo, Chong-Xi Yuan, and Alan Tabrum (2006) “A Swimming Mammaliaform from the Middle Jurassic and Ecomorphological Diversification of Early Mammals” Science 311(5764): 1123-1127.

One final fossil mammal to talk about it Castorocauda, a name that translates into “beaver tail.” The reason is because this small aquatic mammal had a tail much like a beaver. It was broad and flat and even had scales, making it even more beaver-like than the tail of a platypus. Like a platypus, it had sprawling limbs. The forelimbs, in particular, were rather similar to a platypus and were thought to have been used for both swimming and burrowing. The shoulder girdle is also similar to a platypus’s, containing several bones making it stiffer and sturdier than most mammals. The head was rather generic for a small mammal, being rather long and conical (think of a rat’s head in general shape). However, the ear bones of Castorocauda is unlike any found in living mammals. Several of the ear bones are associated with and attached to the lower jaw. In a typical mammal, the lower jaw consists of a single bone (the dentary). In addition, there are three bones in the middle ear: the malleus, incus, and stapes. In Castorocauda, the malleus is actually attached to the dentary through another bone called the surangular. Even though it was attached to the lower jaw, the malleus was probably still involved in hearing. It probably still conducted sound to the incus and stapes. Now, this arrangement is not unique to Castorocauda: it was probably typical of the order Docodonta, which is the order that contains Castorocauda.[14] In fact, there were many types of mammals that had some of their ear bones attached to their lower jaw. It is thought that many of them actually heard sounds, at least partially, through the lower jaw, which would be effective for small, low slung animals that held their heads close to the ground (they would effectively “hear” vibrations coming through the ground).[15] 

These three examples, Repenomamus, Volaticotherium, and Castorocauda, is just a small sample. There were many other types of mammals that fall outside of the groups monotreme, marsupial, and placetal. Other examples include the orders Multituberculata, Haramiyida, and Morganucodonta.

To reiterate, all of these mammals that we have been highlighting come from Mesozoic rocks. As Mesozoic rocks are almost universally agreed by creationists to have been laid down during the Flood, we can safely surmise that these descriptions give us a small glimpse of the pre-Flood diversity of mammals. Since there is barely a trace of these types of mammals in rocks above the Cretaceous, we can conclude that, while they must have been taken aboard the Ark, they probably died out shortly after the Flood.

The loss of this diversity of mammals has severely limited our understanding of the nature of mammals. Placentals so thoroughly dominate mammal diversity today that anything that is not a placental is considered strange, hence why the special, unique platypus gets described as a hodge-podge of various animals. In a world where the Mesozoic animals were still alive, the platypus would seem a lot less strange. Thus, rather than relegating it as an oddball mixture of creatures, we should soberly celebrate it as a remnant of a diversity that has since been lost due to the wickedness of man.Now, I know that “soberly celebrate” is an oxymoron, but I mean it in the same way that a funeral is a mournful event but still a time to celebrate a person’s life. We can celebrate the uniqueness of the platypus, but rather than treating it as a one-off weird-for-the-sake-of-weirdness creature, we can remind ourselves that there used to be many more varieties of mammals, and that much of that staggering variety died off shortly after the Global Flood, which was sent as a punishment due to the wickedness of man. As such, the platypus can be seen as a remnant of a bygone era, not of a prior period of deep time, as the evolutionists do, but rather as a reminder of the diversity of creatures God designed for His original creation.

Thoughts from Steven.


[1]Pian, Rebecca; Micahel Archer; Suzanne Hand (2013) “A new, giant platypus, Obdurodon tharalkooschild, sp. nov. (Monotremata, Ornithorhynchidae), from the Riversleigh World Heritage Area, Australia” Journal of Vertebrate Paleontology 33(6):1255-1259

[2]Ibid.

[3]Grant, Tom (2013) Platypus, CSIRO Publishing, Collingwood, Australia, pg. 5

[4]Musser, A. M. (2003) “Review of the monotreme fossil record and comparison of palaeontological and molecular data” Comparative Biochemistry and Physiology Part A, 136:927-942

[5]Rowe, Timothy; Thomas Rich; Patricia Wickers-Rich; Mark Springer; Michael Woodburne (2008) “The oldest platypus and its bearing on divergence timing of the platypus and echidna clades” Proceedings of the National Academy of Sciences 105(4):1238-1242

[6]Phillips, Matthew; Thomas Bennett; Michael Lee (2009) “Molecules, morphology, and ecology indicate a recent, amphibious ancestry for echidnas” Proceedings of the National Academy of Sciences 106(4):17089-17094

[7]Musser, A. M. (2003) “Review of the monotreme fossil record and comparison of palaeontological and molecular data” Comparative Biochemistry and Physiology Part A, 136:927-942

[8]Just to be clear, by using the term “Mesozoic,” I am not referring to an era of deep time. Rather, I am referring to a unit of rock layers. Rather than interpreting these rock layers as the remnants of a past era, creationists interpret these rocks as representing a sequence of events during the Flood.

[9]Hopkins, Michael (2005) “Prehistoric badger had dinosaurs for breakfast” nature.com, retrieved from https://www.nature.com/articles/news050110-11 on October 2, 2020

[10]Sever, Megan (2005) “Dinosaur-eating mammal” geotimes.org, retrieved from http://www.geotimes.org/mar05/NN_mammalbitesdino.html on October 2, 2020

[11]Celik, Mélina and Matthew Phillips (2020) “Conflict Resolution for Mesozoic Mammals: Reconciling Phylogenetic Incongruence A,ong Anatomical Regions” Frontiers in Genetics 11: 0651

[12]Hu, Yaoming, Jin Meng, Yanqing Wang, and Chuankui Li (2005) “Large Mesozoic mammals fed on young dinosaurs” Nature 433: 149-152

[13]Meng, Jin, Yaoming Hu, Yuanqing Wang, Xiaolin Wang, and Chuankui Li (2006) “A Mesozoic gliding mammal from Northeastern China” Nature 444:889-893

[14]Ji, Qiang, Zhe-Xi Luo, Chong-Xi Yuan, and Alan Tabrum (2006) “A Swimming Mammaliaform from the Middle Jurassic and Ecomorphological Diversification of Early Mammals” Science 311(5764): 1123-1127

[15]Luo, Zhe-Xi; Julia Shultz; and Eric Ekdale (2016) “Evolution of the Middle and Inner Ears of Mammaliaforms: The Approach to Mammals” in Evolution of the Vertebrate Ear: Evidence from the Fossil Record, Jennifer Clack; Richard Fay; and Arthur Popper, eds. SHAR, Volume 59

[8]Just to be clear, by using the term “Mesozoic,” I am not referring to an era of deep time. Rather, I am referring to a unit of rock layers. Rather than interpreting these rock layers as the remnants of a past era, creationists interpret these rocks as representing a sequence of events during the Flood.

[9]Hopkins, Michael (2005) “Prehistoric badger had dinosaurs for breakfast” nature.com, retrieved from https://www.nature.com/articles/news050110-11 on October 2, 2020

[10]Sever, Megan (2005) “Dinosaur-eating mammal” geotimes.org, retrieved from http://www.geotimes.org/mar05/NN_mammalbitesdino.html on October 2, 2020

[11]Celik, Mélina and Matthew Phillips (2020) “Conflict Resolution for Mesozoic Mammals: Reconciling Phylogenetic Incongruence A,ong Anatomical Regions” Frontiers in Genetics 11: 0651

[12]Hu, Yaoming, Jin Meng, Yanqing Wang, and Chuankui Li (2005) “Large Mesozoic mammals fed on young dinosaurs” Nature 433: 149-152

[13]Meng, Jin, Yaoming Hu, Yuanqing Wang, Xiaolin Wang, and Chuankui Li (2006) “A Mesozoic gliding mammal from Northeastern China” Nature 444:889-893

[14]Ji, Qiang, Zhe-Xi Luo, Chong-Xi Yuan, and Alan Tabrum (2006) “A Swimming Mammaliaform from the Middle Jurassic and Ecomorphological Diversification of Early Mammals” Science 311(5764): 1123-1127

[15]Luo, Zhe-Xi; Julia Shultz; and Eric Ekdale (2016) “Evolution of the Middle and Inner Ears of Mammaliaforms: The Approach to Mammals” in Evolution of the Vertebrate Ear: Evidence from the Fossil Record, Jennifer Clack; Richard Fay; and Arthur Popper, eds. SHAR, Volume 59