From dinosaurs to birds: a tail of evolution

Table 1 Caudal vertebral body fusion mouse mutants

Mutant	Affected vertebrae^a					cdl v #^b	Fused ribs	Fused digits	Structure affected				Relevant pathways
Mutant	C	T	L	S	cdl	cdl v #^b	Fused ribs	Fused digits	So	NT	NC	VER	Relevant pathways
Ankrd13a					✓								Nd
Cenpj					✓			✓					Nd
CREB	✓	✓	✓		✓		✓		✓				Notch/Wnt
Dkk1 doubleridge/null			✓	✓	✓			✓	✓				Wnt
Dll3	✓	✓	✓	✓	✓	++	✓		✓				Notch/Wnt
f flexed tail; Sfxn1 mutation			✓	✓	✓	+/-	✓			✓	✓		Bmp/Shh
Fgf3					✓	++			✓	✓			Notch/Wnt
Hes7	✓	✓	✓	✓	✓	++	✓		✓				Notch/Wnt
Ikkα	✓			✓	✓	+		✓					Notch; FGF
Jsr jumbled spine and ribs		✓			✓	++	✓		✓				Notch/Wnt
Knk kinked tail					✓	+					✓		Notch; Wnt
Lrp6 crooked tail					✓	++	✓		✓	✓			Notch/Wnt
mea meander tail		✓	✓	✓*	✓	++							Wnt
Meox1/Meox2					✓	++	✓		✓				Retinoic Acid
Noto			✓	✓	✓	++			✓	✓	✓		Wnt
Nrarp		✓	✓	✓	✓	+	✓		✓				Notch/Wnt
Ppp5c					✓								Wnt
Ror2					✓	+	✓	✓	✓				Notch/Wnt; Wnt
Rpl38	✓	✓			✓	++	✓			✓			Hox
Rps7				✓*	✓	+							nd
Sulf1/Sulf2		✓	✓	✓	✓				✓				Bmp/Shh
Vangl2		✓	✓	✓	✓	++	✓			✓			Wnt
Wnt5a				✓	✓	+++			✓	✓		✓	Wnt

Selected phenotypes and relevant genetic pathways for each mutant are indicated.^aAsterisks indicate fusion other than vertebral body fusion. ^bFor the decreased number of caudal vertebrae (Cdl vertebrae #) column, +: less than half of the tail is absent; ++: half or more of the tail is absent; and +++: tail is severely truncated. Check marks indicate the presence of a particular trait. For a more comprehensive list of posterior vertebral body fusion mouse mutants (those which have fusions posterior to the cervical vertebrae, as seen in modern birds), and for more information on the caudal vertebral body mutants, see Additional files 2 and 3. Abbreviations: C, cervical; cdl, caudal; L, lumbar; NT, neural tube; NC, notochord; nd, not determined; S, sacral; So, somite; v, vertebrae; VER, ventral ectodermal ridge.