Project: Canoville et al._Systemic distribution of medullary bone in the avian skeleton: ground truthing criteria for the identification of reproductive tissues in extinct Avemetatarsalia

About the project

Medullary bone (MB) is an estrogen-dependent, sex-specific tissue produced by female birds during lay and inferred to be present in extinct avemetatarsalians (bird-line archosaurs). Although preliminary studies suggest that MB can be deposited within most skeletal elements, these are restricted to commercial layers or hormonally treated male pigeons, which are poor analogues for wild birds. By contrast, studies in wild bird species noted the presence of MB almost exclusively within limb bones, spurring the misconception that MB deposition is largely restricted to these regions. These disparate claims have cast doubt on the nature of MB-like tissues observed in some extinct avemetatarsalians because of their “unusual” anatomical locations. Furthermore, previous work reported that MB deposition is related to blood supply and pneumatization patterns, yet these hypotheses have not been tested widely in birds. To document the skeletal distribution of MB across Neornithes, reassess previous hypotheses pertaining to its deposition/distribution patterns, and refine the set of criteria by which to evaluate the nature of purported MB tissue in extinct avemetatarsalians, we CT-scanned skeletons of 40 female birds (38 species) that died during the egg-laying cycle, recorded presence or absence of MB in 19 skeletal regions, and assessed pneumatization of stylopods. Selected elements were destructively analyzed to ascertain the chemical and histological nature of observed endosteal bone tissues in “contentious” skeletal regions. Although its skeletal distribution varies interspecifically, we find MB to be a systemic tissue that can be deposited within virtually all skeletal regions, including cranial elements. We also provide evidence that the deposition of MB is dictated by skeletal distribution patterns of both pneumaticity and bone marrow; two factors linked to ecology (body size, foraging). Hence, skeletal distribution of MB is extensive in small-bodied and diving birds, but more restricted in large-bodied species or efficient flyers. Previously outlined anatomical locations of purported MB in extinct taxa are invalid criticisms against their potential reproductive nature. Moreover, the proposed homology of lung tissues between birds and some extinct avemetatarsalians permit us to derive a series of location-based predictions that can be used to critically evaluate MB-like tissues in fossil specimens.

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Rauri Bowie, Matthew Brown, Aurore Canoville, Carla Cicero, John Gerwin, Marcia Kazmierczak , Brian O'Shea, Richard Prum, Nelson Rios, Stephen Rogers, Chris Sagebiel, Mary Schweitzer, Jeremiah Trimble, Lindsay Zanno, Kristof Zyskowski


68 published media groups owned by this project
69 published media groups associated with project specimens
40 project specimens
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cm:birds:s10149, Leptotila cassini

Created 12/10/2018 at 9:20
Modified 12/10/2018 at 9:20
cm:birds:s10506, Antrostomus carolinensis

Created 12/6/2018 at 15:15
Modified 12/6/2018 at 15:15
cm:birds:s11006, Laterallus leucopyrrhus

Created 12/10/2018 at 10:06
Modified 12/10/2018 at 10:06
cm:birds:s11856, Molothrus ater

Created 12/17/2018 at 14:17
Modified 12/17/2018 at 14:18
cm:birds:s12041, Turdus migratorius

Created 12/17/2018 at 13:40
Modified 12/17/2018 at 13:41
cm:birds:s13237, Ardea albus

Created 12/10/2018 at 11:02
Modified 12/10/2018 at 11:03
cm:birds:s13284, Halcyon leucocephala

Created 12/10/2018 at 19:02
Modified 12/10/2018 at 19:02
cm:birds:s14307, Strix varia varia

Created 12/19/2018 at 15:21
Modified 12/19/2018 at 15:21
cm:birds:s14901, Cissa chinensis

Created 12/14/2018 at 13:59
Modified 12/14/2018 at 13:59
cm:birds:s15857, Aethia pusilla

Created 12/10/2018 at 16:57
Modified 12/10/2018 at 16:58
cm:birds:s15978, Phalaropus lobatus

Created 12/10/2018 at 13:16
Modified 12/10/2018 at 13:16
cm:birds:s16123, Alisterus chloropterus

Created 12/17/2018 at 17:44
Modified 12/17/2018 at 17:44
cm:birds:s16508, Cygnus atratus

Created 12/5/2018 at 14:35
Modified 12/5/2018 at 14:35
cm:birds:s16804, Bonasa umbellus

Created 12/5/2018 at 13:30
Modified 12/5/2018 at 13:31
cm:birds:s2794, Corvus brachyrhynchos

Created 12/17/2018 at 10:25
Modified 12/17/2018 at 10:25
cm:birds:s4855, Scolopax minor

Created 12/10/2018 at 13:42
Modified 12/10/2018 at 13:42
cm:birds:s5027, Bubo virginianus

Created 12/17/2018 at 14:53
Modified 12/17/2018 at 14:53
cm:birds:s6632, Coccyzus americanus

Created 12/7/2018 at 10:40
Modified 12/7/2018 at 10:40
cm:birds:s7995, Sterna dougallii

Created 12/10/2018 at 15:49
Modified 12/10/2018 at 15:49
cm:birds:s8375, Dryobates pubescens

Created 12/10/2018 at 20:03
Modified 12/10/2018 at 20:03
cm:birds:s8888, Phaethornis superciliosus

Created 12/6/2018 at 11:01
Modified 12/6/2018 at 11:01
cm:birds:s9081, Micrastur ruficollis

Created 12/11/2018 at 7:53
Modified 12/11/2018 at 7:53
cm:birds:s9815, Psephotus haematonotus

Created 12/11/2018 at 9:24
Modified 12/11/2018 at 9:24
mcz:orn:336971, Crypturellus boucardi

Created 11/29/2018 at 7:41
Modified 11/29/2018 at 7:41
mcz:orn:342774, Tinamus major

Created 11/29/2018 at 10:29
Modified 11/29/2018 at 10:29
mcz:orn:347981, Crypturellus cinnamomeus

Created 11/29/2018 at 9:08
Modified 11/29/2018 at 9:08
mvz:bird specimens:mvz:bird:127163, Nothoprocta ornata ornata

Created 11/28/2018 at 20:10
Modified 11/28/2018 at 20:10
mvz:bird specimens:mvz:bird:127168, Tinamotis pentlandii

Created 11/28/2018 at 21:33
Modified 11/28/2018 at 21:33
mvz:bird specimens:mvz:bird:138066, Nothocercus bonapartei intercedens

Created 11/28/2018 at 22:21
Modified 11/28/2018 at 22:21
ncsm:ncsm-birds:10222, Meleagris gallopavo

Created 11/29/2018 at 11:06
Modified 11/29/2018 at 11:06
TMM:M:11422, Ptilinopus melanospilus

Created 12/3/2018 at 13:48
Modified 12/3/2018 at 13:48
TMM:M:11960, Coccyzus americanus

Created 12/4/2018 at 16:51
Modified 12/4/2018 at 16:51
TMM:M:12926, Tyrannus verticalis

Created 12/5/2018 at 12:07
Modified 12/5/2018 at 12:07
TMM:M:5395, Anas luzonica

Created 12/3/2018 at 10:55
Modified 12/3/2018 at 10:55
TMM:M:6536, Colinus virginianus

Created 11/30/2018 at 8:44
Modified 11/30/2018 at 10:35
TMM:M:6956, Colinus virginianus

Created 12/3/2018 at 9:34
Modified 12/3/2018 at 9:34
TMM:M:6977, Lonchura punctulata

Created 12/5/2018 at 10:55
Modified 12/5/2018 at 10:55
TMM:M:8889, Limnodromus griseus

Created 12/4/2018 at 19:07
Modified 12/4/2018 at 19:07
TMM:M:8909, Cardinalis cardinalis

Created 12/5/2018 at 9:58
Modified 12/5/2018 at 9:58
YPM :vz:ypm orn 148246, Rhea americana intermedia

Created 11/28/2018 at 13:38
Modified 11/29/2018 at 8:25