Science - USA (2022-06-03)

(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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