(unnumbered IVPP specimen), and a bovid
horncore of ?Turcocerussp. (small form) were
sectioned tangentially and horizontally using
standard techniques. The specimens were cut
into small pieces and embedded in resin and
then further sectioned using a professional
cutting system, resulting in thin slices (~8 to
10 mm). Histological slices were observed and
imaged using a polarized light microscope.
Cladistic analysis
Cladistic analyses were performed to test the
phylogenetic hypothesis among various pecoran
groups. The data matrix contains 45 taxa, in
whichHyemoschus aquaticuswas selected as
the outgroup. The characters are combined
with morphological and DNA data. The 110
morphological characters (data S2) were based
on several references ( 13 , 18 , 25 , 34 , 35 )and
self-compiled; and the DNA data were from
Hassaninet al.( 36 ). Two methods, Bayesian
Wanget al., Science 376 , eabl8316 (2022) 3 June 2022 8of10
Age (Ma)
Early Miocene Middle Miocene Late Miocene Pliocene
Pleistocene
Holocene
GiraffomorphaGiraffoideaCervoidea Antilocapridae + Bovidae
Hoplitomerycidae
Mid Miocene
Climate Optimum
Early Pliocene
Climate Optimum
dMiocen
mmate Optim
oocen
OOptim
appearance of
Discokeryx
appearance of
Giraffa
Accumulative number of headgears
14
12
10
8
6
4
2
0
20 15 10 5 0
A
Giraffomorpha Bovidae Cervoidea
Hornless pecorans Perissodactyla Proboscidea Suiformes
D. xiezhi
other herbivores
other ruminants
Climacoceratidae indet.
Giraffidae indet.
δ^13 C (‰)
δ
18
O (‰)
C
-12 -10 -8 -6 -4
2
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
0
-2
-4
-6
-8
-10
-12
-14
-16
-14 -12 -10 -8 -6 -4
Junggar Region Linxia Basin Tunggur Region
Discokeryx xiezhi Dalanggou Tairum Nur
Halamagai Laogou Moergen
δ
18
O (‰)
δ^13 C (‰)
D
Axis
CV III
a
b
c
c
d
d
e f
f
h
i
i j
j
k
g
Centrum length (mm)
Lower cheek tooth row length (mm)
350
300
250
200
150
100
50
0
80 100 120 140 160 180 200 220
B
Fig. 6. Head-neck morphology and ecology of ruminants.(A) Headgear
diversity (accumulative numbers, shown as step lines) of ruminant groups during
the late Neogene, in which the giraffoids exhibited more diversity in headgear
morphology than the other pecoran groups; notably, bothDiscokeryxandGiraffa
appeared during important paleoenvironment events. Giraffomorpha = Giraffoidae +
Palaeomerycidae, sensu Sánchezet al., 2015. (B) Morphological variations of the
giraffoid axis and the third cervical vertebra, in which the sample points represent
the average centrum length (the vertical coordinate) versus average lower cheek
tooth row length in each taxon (the horizontal coordinate) (error bars represent
standard deviations). Lowercase letters correspond to the following: a,Climacoceras
gentryi;b, Giraffokeryx punjabiensis;c, Orangemeryx hendeyi;d, Decennatherium rex;
e, Canthumeryx sirtensis;f, D. xiezhigen. et sp. nov.; g,Okapia johnstoni;h,
Giraffa camelopardalis;i, Samotherium sinense;j, Samotherium major;andk,
Bramatherium megacephalum). ( C) Stable isotope ratios of the tooth enamel in the
Halamagai herbivore community, the crosses representing the standard deviations,
and (D) those of the early-middle Miocenecommunities from northern China
[data from Wang and Deng and Zhanget al.( 47 , 48 )]. The dashed box indicates the
area occupied byD. xiezhi, showing no overlap with other herbivores, which
suggests thatD. xiezhimay have occupied different niches than its contemporary
herbivores. Data sources: Table 1 and data S6 and S7.
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